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Problems of Ammonite Nomenclature

VIII. On Ammonites cordatus and A. serratus, J. Sowerby

Published online by Cambridge University Press:  01 May 2009

L. F. Spath
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Extract

The International Rules of Zoological Nomenclature aim at the “elimination of all possibilities of discussion”; and in troubled times like the present, when it is impossible to secure decision on a knotty problem by the International Commission, automatic solution of any nomenclatorial difficulty should be particularly welcome. We all know of certain genera that have caused trouble to revisers because they were based on several species, subsequently found to belong to more than one genus; likewise species have often been based on a number of differing specimens, some of which have in course of time been relegated to other species or genera. Now Opinion 88 claims that the procedure to be followed in such cases is well known, but on this point there appears to be some doubt, and I therefore propose to discuss the two species mentioned in the above title1.

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Information
Geological Magazine , Volume 80 , Issue 3 , June 1943 , pp. 111 - 117
Copyright
Copyright © Cambridge University Press 1943

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References

1 Both were described in 1813 in vol. i of Mineral Conchology, p. 51, p1. xvii, figs. 2 and 4 (Amm. cordatus) and p. 65, p1. xxiv (Amm. serratus).Google Scholar

2 Les Céphalopodes du Jura et du Crétacé inférieur de la Sibérie septentrionale. Mém. Acad. Sci. St. Pétersb., ser. viii, xxi, No. 4, 1914, 48.Google Scholar

3 Type Ammonites, iii, 1920, 10, 15. I am using Cardioceras cardia Buckman in preference to C. subcordatum, Pavlov, because Amm. subcordatus, d'Orbigny, is also a Cardioceras in continental literature, and it would be very misleading to use subcordarum as a zonal or sub-zonal index (Spath, 1935, p. 15).Google Scholar

4 Pal. Universalis, ser. ii, fasc. 1, 1905, Nos. 94, 94a.Google Scholar

5 Note on the Type-specimens of Amm. cordatus and Amm. excavatus, Sowerby, J.. Geol. Mag., xlvii, 1910, 503–5.Google Scholar

1 The Ammonite Zones of the Upper Oxfordian of Oxford, and the Horizons of the Sowerby's and Buckman's Types. Quart. Journ. Geol. Soc., xcii, 1936, 152. See also Monograph Corallian Ammonites, pt. viii, 1942, 243.Google Scholar

2 See Spath, , The Ammonite Zones of the Upper Oxford Clay of Warboys, Huntingdonshire. Bull. Geol. Surv., No. 1, 1939, 88 (footnote 1).Google Scholar

3 The Upper Oxford Clay at Purton, Wilts, and the Zones of the Lower Oxfordian. Geol. Mag., lxxviii, 1941, 169.Google Scholar

4 See No. iv of this series, Geol. Mag., lxxvi, 1939, 77.Google Scholar

1 I.e. a form having the characteiistic undulations near the circumference, persisting to about 75 mm. diameter (the figure is slightly reduced) and a fiveangled cross-section. The ribbing on the inner whorls is the same in all the forms of Prionodoceras from the serratus zone.

2 Type Ammonites, iii, 1920, p1. 155 (“Prionoceras”). Buckman's P. excentricum (Geol. Mag., v, 1924, p1. 464) seems to be merely an individual variation of P. prionodes.Google Scholar

3 Report on Ammonites collected at Long Stanton, Cambs., and on the Age of the Ampthill Clay. Summ. Progr. Geol. Survey for 1935, pt. ii (1937), 67. Also: Monograph on the Ammonites of the English Corallian Beds, pt. iii, Pal. Soc., 1937, 50.Google Scholar

1 Blake, in 1875, spoke of Amm. serratus as being “ plentiful”, and he recorded a peculiar form of that species “like Sowerby's original”, occurring “in abundance” in Lincolnshire. Elsewhere, he spoke of Amm. serratus“of the Sowerbyan form” in Yorkshire, (On the Kimmeridge Clay of England. Quart. Journ. Geol. Soc., xxxi, 1875, 208, 209, 210).Google Scholar

2 Monographie der Gattung Cardioceras. I. Zeit. Deutsch. Geol. Ges., lxvii, 1915, 172–5, p1. xviii, figs. la-c.Google Scholar

3 The Upper Jurassic Invertebrate Faunas of Cape Leslie, Milne Land. I. Oxfordian and Lower Kimmeridgian. Medd. om Grønland, 99, No. 2, 1935, 12–25.Google Scholar

4 A rival Amm. serratus was created by Parkinson in 1819.Google Scholar

5 A specimen of Amm. serratus (B.M. No. 66341) bears his own identification “Amm. stokesi, M.C. 191”, which is interesting in view of the fact that Roemer (1836) united Amm. serratus with Amm. amaitheus, Schlotheim (i.e. the German equivalent of Amm. stokesi).Google Scholar

6 On the Muscular Attachment of the Animal to its Shell in some Fossil Cephalopoda (Ammonoidea). Trans. Linn. Soc., 2nd ser., Zool., vii, pt. 4, 1898, 75, 86, p1. xviii, figs. 8–10, p1. xix, figs. 1, 2.Google Scholar

7 Jurassic Rocks of Britain, V. Mem. Geol. Surv., 1895, p. 56 (cited as Amm. cordatus, var. excavatus).Google Scholar

1 The Jurassic Rocks of the Neighbourhood of Cambridge, 1892, p. 50.Google Scholar

2 Supplement to the Geology of Weymouth, 1888, p1. xv, fig. 5.Google Scholar

3 Type Ammonites, vi, 1927, p1. 704.Google Scholar

4 The presence of glue on the last septal surface shows that part of the outer whorl has been detached and apparently discarded.

1 The specimen is too badly corroded after that stage.

2 Description de Ia Faune des Sables jurassiques supérleurs du Calvados. Mém. Soc. Linn. Normandie, xxi, 1904, 17, p1. 1 (iv), figs. 13, 13a (Cardioceras alternans var. glosensis).Google Scholar

3 Zur Ammoniten-Fauna des Petschoraschcn Jura. Mém. Com. géol. St. Pétersb. N.S., 76, 1912, 60, p1. ii, fig. 4 (lectotype).Google Scholar

1 Op. cit. (Milne Land, i), 1935, p. 25. The “ trituberculate ” stage in this species begins at a diameter at which A. (P.) serratum is already becoming smooth. The outer nodes are less projected than in A. (P.) glosense, more angular, and increase in prominence with age.

2 Revision of the Jurassic Cephalopod Fauna of Kachh. Mem. Geol. Surv. India, Pal. Indica., N.S., ix, No. 2, part vi, 1933, 863, 868.Google Scholar

3 Type to be Damon's original in the British Museum (N.H. No. C. 3305) ; see footnote 2, p. 115.

4 In the Table of Ammonite Zones given in 1935 (Spath, op. cit., Milne Land, i, 74) the species of Amoeboceras of the anglica zone should have been A. marstonense, which is associated in the same bed with A. (P.) ogivale, Buckman sp. (Type to be Damon's original in the British Museum (N.H. No. C. 3305) ; p. 18, footnote 1) and undescribed forms.