Six common supra-littoral Protista from the island of Cumbrae are described and details given of their cultivation. Chlorophyceae: Nannochloris oculata n.sp., Brachiomonas submarina var. pulsifera n.var.; Cryptophyceae: Hemiselmis virescens n.sp.; Chrysophyceae: Syracosphaera elongata n.sp., Microglena arenicola n.sp., Mallomonas epithalattia n.sp.

Akera bullata O. F. Müller is a tectibranch mollusc having a coiled external shell and a foot with lateral extensions used for swimming. At certain times of the year it swims actively, as was observed by Donovan, who writes that it ‘sports in its watery element with all the liveliness of a butterfly, and formed a pleasing object when kept alive in a glass of sea water’ (quoted by Montagu, 1803). Although sometimes abundant locally, it is not a mollusc often taken by the collector, even though it is a conspicuous object when swimming.

In a recent short note in this Journal (Fraser, 1954) the occurrence was announced, off the entrance to the English Channel, of the solitary form of the salp Ritteriella picteti (Apstein), and seven aggregate forms of R. amboinensis (Apstein), taken by H.M.S. Challenger in 1953. The identification of the aggregate forms as R. amboinensis and not as R.pictetiv/as based, as then stated, on Thompson's (1948) description from a very young specimen of R. picteti which emphasized the similarity of its muscle arrangements to those of Salpa cylindrica and not to Ritteriella amboinensis.

Since this was written, Berner (1954) has described the aggregate form of R. picteti from good specimens found off the west coast of U.S.A., and he has shown that the musculature was in fact not like that of Salpa cylindrica but very similar to Ritteriella amboinensis. Differences were noted in the number of fibres constituting the various body muscles and in the number and arrangement of the oral muscles. A still more recent paper by Yount (1954) includes comparisons of the two forms, based on Berner's characters but also including differences in the length of the endostyle and in body shape (length of anterior and posterior processes, and degree of extension of the gut outside the rest of the body). Yount also goes into greater detail in describing the oral musculature in tie two species.

A re-examination of the specimens taken by H.M.S. Challenger shows them to be in fairly close agreement with both Berner's and Yount's descriptions of R. picteti, but with one or two small differences. The actual number of fibres in the muscles is rather smaller than given by Berner for R. picteti, though the precise figure is difficult to ascertain, and there is no median interruption of the first sphincter muscle in the upper lip which Berner believed to be characteristic, and which Yount accepted.

Apart from a few scattered observations (Hensen, 1887; Gran, 1902) the study of the food of Calanus began with Dakin (1908). He examined the remains present in the gut, and this was the method used also by Esterly (1916), Lebour (1922) and Marshall (1924). They all found that these remains consisted of a greenish mush containing the skeletons of numerous planktonic organisms, chiefly diatoms and dinoflagellates. Naked flagellates were, how-ever, occasionally seen, and it was realized that the food might in reality consist largely of organisms which had no skeleton and could leave no recognizable remains.

The family Otinidae is the smallest and probably the least known among the pulmonates. Thiele (1931) places it at the base of the Basommatophora, the more primitive order of the subclass Pulmonata, in the Stirps Actophila. It contains a single species, Otina otis Turton, with a geographical range confined to the coasts of the British Isles and north-west France. Its northern distribution reaches as far as the Firth of Clyde, according to Jeffreys (1869), and over the greater part of its British range it appears to follow fairly closely the distribution of the barnacle Chthamalus stellatus, which here reaches its northern limit. Otina otis is a tiny snail, and its external form is limpet-like. The shell, which is well described by Jeffreys (1869), and also by Ellis (1926), measures up to 2*5 mm in length, with a short apical visceral coil at the posterior end. It is dark chestnut brown in colour, and most resembles a minute Haliotis.

Rothschild (1935) reported that Dr M. V. Lebour drew her attention to a ‘huge-tailed’ monostome which had occurred during 1931 in specimens of Turritella communis collected from the Rame Mud, Plymouth. From 1932 to 1934 Rothschild (1935) examined 541 specimens of this gastropod from that locality without finding this larva. During the summer of 1952, the present author examined a number of specimens from the same locality and was also unsuccessful in finding such a larval trematode. However, in November 1952, the monostome described below was found in two of 110 Turritella collected from Cawsand Bay, Plymouth Sound.

The author wishes to express his indebtedness to the Director and Staff of the Plymouth Laboratory of the Marine Biological Association for their friendly co-operation and assistance in all phases of this work. The work was carried out while the author was holding a Fulbright Scholarship.

METHODS

Fully developed cercariae were obtained by isolating infeaed specimens of T. communis in jars of sea water and allowing the cercariae to emerge. Rediae and immature cercariae were obtained by crushing the shells of the hosts. Living specimens as well as permanent preparations were studied. Whole mounts were fixed in sublimate, stained with borax-carmine, and mounted in Canada balsam, or fixed in sublimate or formalin, unstained, and mounted in Faure's medium or in Cristalite (E. Gurr). Serial sections (5 /x) of several cercariae were stained with Ehrlich's haematoxylin and eosin. The orientation of the objects in the desired position at imbedding was achieved by the method of Peterfi (after Romeis, 1948, p. 99). The incidence of infection was determined by crushing the gastropods and examining the digestive glands and gonads under the dissecting microscope.

During the course of earlier work with larvae of Ophelia bicornis Savigny it became increasingly clear that a major factor in stimulating these larvae to settle and metamorphose is the presence, on sand grains of suitable size, of living micro-organisms such as bacteria, in numbers neither too many nor too few (Wilson, 1954). It had been shown that an acid-cleaned sand (which is neutral or almost so) kept in sea water becomes increasingly attractive to these larvae with time. It had been admitted, however (loc. cit., p. 366), that these results were derived from a comparison of experiments not designed to this end, and that further tests, planned for the purpose, were desirable.

Living specimens of Petricola pholadiformis Lamarck were obtained from Burnham-on-Crouch, Essex.

Studies of the principal organ systems were made on the living animal, particular attention being paid to the ciliary feeding and cleansing mechanisms in the mantle cavity, and the ciliary sorting mechanisms within the stomach. The action of the bulbus on the posterior aorta was also studied.

A detailed comparison was made between P. pholadiformis and all the British species of Pholadidae. Thirty anatomical features were found in which P. pholadiformis differed from all of the Pholadidae, and fourteen features in which P. pholadiformis resembled one or more species of Pholadidae. It was concluded that these resemblances were purely fortuitous.

Nereis diversicolor is typically euryhaline: it is in equilibrium with normal sea water (Schlieper, 1929; Beadle, 1937), and develops hypertonicity in more dilute media which it is able to maintain indefinitely. The maintenance of this steady state is preceded by a transition period. During this there is a rapid uptake of water accompanied by a loss of salts from the worm, resulting in a fall in the osmotic pressure of the body fluids, and then a subsequent water loss which, according to Ellis (1937), is not accompanied by an uptake of salts. Worms accommodated to 25% sea water weigh about 140% of their original weight (Beadle, 1931). Beadle (1937) found that when the steady state is attained the body fluid concentration in 50% sea water approaches a value which is about 5% higher than that of the external medium, whereas in 25% sea water the concentration of the body fluid is equivalent to about 44% sea water. His worms were collected from the Northumberland coast, and concentration measurements of the body fluid were determined by Baldes's modification of the Hill vapour-pressure method. The results of Schlieper (1929) on worms from Heligoland, where they may live in a salinity as low as 4%, are based on freezing-point determinations and give a higher internal concentration in the dilute media: after 3 days in 50% sea water the concentration of the body fluid is equivalent to 68% sea water, and after 2 days in 25% sea water equivalent to 49% sea water. These varying results suggest the occurrence of local physiological races.

The sampler to be described takes a small unstratified sample of the sea-bed, the sample being subject to a minimum of loss while being brought up. Such samples are of use in survey work, or for studies on grade size, mineralogical composition, chemical properties, or microfauna and flora of the deposits.

Although core-samples, in which the original stratification is retained, can be taken in soft muddy sediments without difficulty, it is not at all easy to take cores of sand or gravel. On such deposits an unstratified sample may be the best that can be obtained. Coarse sediments may be sampled by a dredge fitted with canvas bag, but when a small sample is required quickly, a light instrument which can be lowered vertically from the ship on a rope or hydro-graphic wire is needed. ‘Snapper’ samplers do not always take a satisfactory sample as the jaws may be prevented from closing by a pebble or shell wedged between them, much of the sample being lost while hauling up (cf. Stetson, 1938, p. 7). Stetson describes an instrument which takes a small semicircular core of sediment, the sample being sealed in the coring tube while being brought up, so preventing any loss of material. While no doubt taking good samples, the instrument is rather heavy (57 kg) and complicated in construction.

Nereis diversicolor is typically euryhaline: it is in equilibrium with normal sea water (Schlieper, 1929; Beadle, 1937), and develops hypertonicity in more dilute media which it is able to maintain indefinitely. The maintenance of this steady state is preceded by a transition period. During this there is a rapid uptake of water accompanied by a loss of salts from the worm, resulting in a fall in the osmotic pressure of the body fluids, and then a subsequent water loss which, according to Ellis (1937), is not accompanied by an uptake of salts. Worms accommodated to 25% sea water weigh about 140% of their original weight (Beadle, 1931). Beadle (1937) found that when the steady state is attained the body fluid concentration in 50% sea water approaches a value which is about 5% higher than that of the external medium, whereas in 25% sea water the concentration of the body fluid is equivalent to about 44% sea water. His worms were collected from the Northumberland coast, and concentration measurements of the body fluid were determined by Baldes's modification of the Hill vapour-pressure method. The results of Schlieper (1929) on worms from Heligoland, where they may live in a salinity as low as 4%, are based on freezing-point determinations and give a higher internal concentration in the dilute media: after 3 days in 50% sea water the concentration of the body fluid is equivalent to 68% sea water, and after 2 days in 25% sea water equivalent to 49% sea water. These varying results suggest the occurrence of local physiological races.

The optic cushion of Marthasterias glacialis is seen to contain yellowish orange and reddish orange pigments. The former occurs throughout the cushion, the latter is confined to the wall of the optic cups and a few scattered, irregular patches. Both pigments occur in the cytoplasm of long and narrow or irregular cells, some in the form of granules or vacuoles.

Optic cushions yield an orange extract in methanol which decomposes in light.

The behaviour of methanolic extracts after partitioning, saponification, chromatographic separation and spectrophotometric examination indicates the presence of β-carotene and esterified astaxanthin.

The significance of the results in relation to previous findings and their possible bearing on photoreception is discussed.

These notes arise from the difficulty met with in identifying a pinkish encrusting sponge which has been frequently collected by hand from rocks at 5–10 fathoms. The sponge was at first identified, by a process of elimination, with the deep water genus Inflatella. Fortunately some preparations were shown to Dr Lévi at Roscoff to whom the species was at once familiar as Stylotella columella (Bowerbank). It was then found that this species had been described originally by Bowerbank from an Exmouth specimen, and subsequendy by Topsent from both south and west coasts of France. Topsent found the unusual, if not unique, character of this sponge in possessing, besides siliceous spicules, a great abundance of calcareous granules. These granules are almost certainly the ‘gemmules’ described and figured by Bowerbank. De Laubenfels in 1928 collected one specimen from Plymouth Sound which he identified as Stylotella columella; but proposed (1932) that the species should be included in the genus Prianos Gray. Burton in 1934 renamed the species Hemimycale columella, figuring the spicules as styles. Arndt (1935) returned to Stylotella and retained Burton's figure of the spicules. As the styles have been found, so far, only as a small minority amongst the spicules, it has been thought worth while to provide a further description; and to discuss the differing views on the systematic position of the species.

The logarithmic transformation has been used in the statistical analysis of certain marine biological data. Parameters calculated from the transformed distributions have been used in the description of the observations, but it appears that some of the mathematical procedures adopted have not been fully understood.

Winsor & Clarke (1940) have analysed data from plankton hauls. The problem considered by them was the determination of the variability in numbers of animals caught by repeated hauls through the same body of water. The raw data were characterized by a constant coefficient of variation, i.e. the variability in catch was proportional to the size of the catch. By transformation from the actual numbers caught to their logarithmic values, it was possible to equalize the variances and to apply the method of analysis of variance to esti-mate the variability due to the different sources. Finally, an estimate of the coefficient of variation was obtained from the logarithmic values. Their method of estimation was quoted by Snedecor (1946, p. 451) and was employed by Barnes & Bagenal (1951) in their study of repeated trawl hauls. Barnes & Bagenal also calculated confidence limits for comparison of observations following the method of Silliman (1946) in his work on pilchard eggs. These methods seem to be based on a misunderstanding of the nature of a trans-formation. The formal relation between the variance of such transformed data and the coefficient of variation of the untransformed data follows from the moments of the ‘log-normal’ distribution, given first by Wicksell (1917). From these moments it will be shown that the method given by Winsor & Clarke is mathematically unsound.

During investigations into the endocrinology of Leander ( =Palaemon) serratus (Pennant) several differences in physiology (which will be reported in this Journal at a later date) have been found between the prawns from Plymouth and those from Roscoff on the north coast of France. These experiments involved the repeated handling and the close examination of about a thousand prawns from Roscoff and many more from Plymouth. Increasing familiarity with these animals led to the realization that the two samples could readily be distinguished by eye. It was not always possible to determine the provenance of a single individual in this way, but any group of five or six could be told at a glance. A detailed examination of the external morphology showed that the characteristic differences by which the provenance of these animals could be determined lay not in any anatomical feature but in the disposition and arrangement of the chromatophores which form the pattern on the dorsal side of the cephalothoracic shield and the anterior part of the abdomen. Great individual variations were to be seen, but differing trends of development of the patterns were found in the two populations. There was some degree of overlap between the populations, but only about 15% of the prawns lay in this region of overlap and thus failed to bear the marks of their locality; the remaining 85% could be assigned to either Roscoff or Plymouth with little difficulty. Recently I have been able to examine about forty prawns from Concarneau, on the Atlantic coast of France, and these again are mostly different from either of the other two samples.

There is a considerable literature on the ecology of intertidal animals and a growing one on the sublittoral fauna. Largely because of the difficulty of taking samples in very shallow water, little attention has been paid to the continuation of the intertidal zonation below the low-water mark. Although incomplete in some respects, the results of the present survey are published, partly to help bridge the gap between studies of sublittoral and intertidal faunas, partly because it is unlikely that this survey will ever be completed and partly because the intertidal fauna of one of the bays is particularly well known. The work was begun in 1938 by one of the authors (A.M.) but was discontinued at the outbreak of the late war. Since 1949 further collections have been made and the identity of most of the species taken in the earlier sampling has been checked. The collections of animals and a full account of the results have been deposited in the Marine Laboratory at Millport.

The ages of 1426 female, and 135 male Long Rough Dabs have been determined from otolith readings. The females were found to live into their seventh year and reach 30.5 cm, compared with males that live to their fifth year and reach 19.0 cm in length. However, the mean increase in length per year for a given length, has been found to be the same. The growth of the females has been shown to fit the equation lt=26.437 (I—0.574t) and of the males lt=17.754 (I —0.585t). In the case of the females the observed and calculated values agree quite closely, but with the males there is a greater difference, and it is believed that the discrepancy is due to net selection. The suggestion is made that the calculated mean lengths for each age group are better estimates of those of the population than are the observed sample means. The two standard deviations limits can be estimated about the population means and the sample values are found to be within these limits.

Comparison with previous studies shows that the Clyde fish are smaller and shorter-lived than more northern specimens, though broadly speaking the rate of growth for comparable ages is not so dissimilar.

There is a considerable literature on the ecology of intertidal animals and a growing one on the sublittoral fauna. Largely because of the difficulty of taking samples in very shallow water, little attention has been paid to the continuation of the intertidal zonation below the low-water mark. Although incomplete in some respects, the results of the present survey are published, partly to help bridge the gap between studies of sublittoral and intertidal faunas, partly because it is unlikely that this survey will ever be completed and partly because the intertidal fauna of one of the bays is particularly well known. The work was begun in 1938 by one of the authors (A.M.) but was discontinued at the outbreak of the late war. Since 1949 further collections have been made and the identity of most of the species taken in the earlier sampling has been checked. The collections of animals and a full account of the results have been deposited in the Marine Laboratory at Millport.

The name Codium tomentosum (or its nomenclatural synonym C. dichotomum) has been applied to dichotomous representatives of the genus in the British Isles ever since the genus was established by Stackhouse in 1797. The purpose of this paper is twofold: to show that three distinct species are involved; and to clarify the nomenclature.

I am grateful to the directors and curators of the following herbaria for the loan of specimens: British Museum (BM); Royal Botanic Garden, Edinburgh (E); Farlow Herbarium, Harvard University (FH); University of Glasgow (GL); Royal Botanic Gardens, Kew (K); Rijksherbarium, Leiden (L); Linnean Society of London (LINN); University of Michigan (MICH); New York Botanical Garden (NY); University of Oxford (OXF); Museum National d'Histoire Naturelle, Laboratoire de Cryptogamie, Paris (PC); Marine Bio-logical Association, Plymouth (PL); Naturhistoriska Riksmuseet, Stockholm (S); Trinity College, Dublin (TCD); University of California, Berkeley (UC); United States National Museum (US). Liquid-preserved and dried material, which has been placed in the Herbarium of the University of California, was kindly provided by Dr Sheila Lodge, Dr Betty Moss, Dr Mary Parke, Dr Mairfn de Valera, and Dr M. A. Wilson. Special thanks are due to Dr Mary Parke for her sustained interest, encouragement, and help in this study