The evolution of the life cycles of the members of the family Dipetalonematiidae Wehr, 1935 (Filarioidea) is considered in the light of existing knowledge of spirurid nematodes. The hypothesis that the life cycles of the dipetalonematids originated from life cycles similar to those of Draschia megastoma, Habronema muscae and H. microstoma is considered to be incorrect. Alternatively, it is pointed out that in the primitive subfamily Thelaziinae Baylis and Daubney, 1926 there are forms with typical spiruroid life cycles (Rhabdochona ovifilamenta), forms with life cycles approaching those of the dipetalonematids (Thelazia spp.), and forms with life cycles intermediate between these two (Oxyspirura spp.). It is suggested that intestinal species similar to Rhabdochona gave rise to the more specialized spiruroids and forms that left the gut (Oxyspirura, Thelazia) gave rise to the dipetalonematids.

The dipetalonematids are believed to have originated from nematodes resembling the species of Thelazia and having life cycles like those of T. rhodesii, T. skrjabini and T. gulosa. Some of these worms established themselves in subcutaneous tissues. Like Parafilaria multipapillosa, they released their eggs through a break in the skin of the definitive host, thus causing a skin lesion that attracted various haematophagous arthropods which finally became involved as intermediate hosts in the life cycle. Certain species like the members of Parafilaria and Stephanofilaria (?) came to rely upon intermediate hosts that were unable to break the skin of the definitive host (Musca) and cutaneous lesions became permanent features of their life cycles. Other species became dependent upon intermediate hosts that could puncture the skin (mosquitoes, simuliids etc.) and skin lesions became unnecessary to the life cycle. The larvae of these worms then began to spread into the tissues of the skin, as found in Stephanofilaria, Onchocerca, and some species of Dipetalonema, and the infective larvae developed the ability to penetrate into the wound made by the intermediate host and perhaps, in some cases, the intact skin. Ultimately the larvae of some species habitually entered, or were deposited into, the blood stream and the adult worms were then free to colonize the vertebrate body as their larvae would then be available to the intermediate host no matter where the latter fed on the body of the definitive host; this group of worms gave rise to the many members of the family Dipetalonematidae.

The family Filariidae Claus, 1883 is briefly reviewed in the light of the above hypothesis. It is pointed out that many species, e.g. Diplotriaeninae Skrjabin, 1916, live in the air sacs of reptiles and birds and probably have life cycles similar to that of Diplotriaenoides translucidus, i.e. the eggs pass through the lungs, up the trachea and out in the faeces. It is thought that these forms may represent a separate line of evolution from that which gave rise to the Dipetalonematidae. Certain genera (Lissonema, Aprocta), occurring in the orbits of birds, probably have life cycles like Thelazia or Oxyspirura. Many other genera occurring in superficial muscles and subcutaneous tissues (Squamofilaria, Ularofilaria, Tetracheilonema, Pelecitus, Monopetalonema) may release their eggs through some sort of skin lesion. Studies on these forms are urgently needed as the details of their life cycles may shed fresh light on the origins of the more specialized filarioids.

In 1939 the sugar-beet nematode, Heterodera schachtii Schmidt, 1871, was found attacking the roots of sugar beets in the Blackwell district near Sarnia, Ontario. Studies were started in 1947 on the control and biology of this cyst-forming nematode, including the susceptibilities of various cultivated and weed plants to the nematode. Susceptibility was based on the presence or absence or degree of infestation of gravid white females on the roots.

1. Ignavia venusta de Freitas is recorded from the kidneys of two Fish-eagles (Cuncuma vocifer) and a Goliath heron (Ardea goliath) from the Southern Sudan.

2. Ignavia is regarded as a valid genus and to it is transferred Allechinostomum renale Yeh, 1954.

3. Ignavia inops de Freitas (= Echinostomum sp.inq. Dietz, 1910) probably does not belong to the genus Ignavia or even to the subfamily Echinochasminae.

4. A new species of Renicola is described from the kidney of the Goliath heron and is named R. goliath.

5. The affinities of R. goliath are discussed and R. brantae McIntosh and Farr, 1952 is figured.

6. The significance of the occurrence of these two flukes in the Southern Sudan is discussed.

(1) Cercaria splendens Szdiat was found in a specimen of Planorbis vortex, caught in a ditch near Utrecht, the Netherlands.

(2) Its morphology and behaviour are briefly described and compared with the data given by previous authors.

(3) A feeding experiment with the stickleback, Gasterosteus pungitus, is described. The preliminary conclusion is drawn that Gasterosteus is not the final host but probably acts as a transport host for this species.

1. Sandonia sudanensis gen. et sp. nov. obtained from the intestine of the freshwater fishes Synodontis schall and Distochodus niloticus in the Nile is described and its affinities with the members of the subfamily Schizamphistominae are discussed.

2. Brevicaecum niloticum gen. et sp. nov. from the intestine of Citharinus citharus from the Nile is described and placed in the subfamily Kalitrematinae.

A new species Fibricola sarcophila, is described from Sarcophilus harrisii from Tasmania. The history of previous records of strigeid from marsupial hosts is outlined and their possible relationships discussed.

Brachylaemus dasyuri (Johnston, 1912) is recorded from Thylacis obesulus (Shaw & Nodder, 1797) from Queensland. It is redescribed and Brachylaemus simile (Johnston, 1912) is confirmed to be a synonym.

A review is made of the species of Brachylaemus recorded from American and Australian marsupials. It seems probable that they have arisen from a common ancestral type parasite in an ancestral marsupial.

P. 126. For ‘Homa fish’ read ‘mud-fish.’

P. 129. For ‘Homa fish’ read ‘Mud-fish, Clarias gariepinus (Burchell).’