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doi: 10.1111/j.1096-3642.1956.tb00481.xpmid: N/A
A group of typical bony rays associated with a bony mass representing fused radial bones was found in the middle of the adipose fin of an otherwise normal, fully‐grown Synodontis membranaceus.
doi: 10.1111/j.1096-3642.1956.tb00482.xpmid: N/A
1 The normal behaviour pattern of Bufo regularis while moulting is described. 2 The frequency of moulting has been determined in various conditions. At 20° C. these toads moult once every four to seven days. The frequency of moulting is not influenced by size, age or feeding, nor does there appear to be any difference in this regard between the sexes; any seasonal variation is slight. 3 The frequency of moulting is greater at higher temperatures. Abrupt changes of temperature do not upset the moulting rhythm. 4 At 25° C. less than an hour before moulting the toads pale markedly. The return to normal coloration is slower, taking more than four hours. 5 The frequency of moulting is higher in toads kept in constant light than in those in constant darkness. In conditions of alternating light and dark there is a well marked preference for moulting during the hours of illumination at 25° and 30° C., but at 20° C. the effect is abolished. It is suggested that light can trigger the events which lead to the shedding of the skin.
doi: 10.1111/j.1096-3642.1956.tb00483.xpmid: N/A
A new hydroid, resembling the hydroid of Cladonema radiatum in possessing only an oral whorl of capitate tentacles and an aboral whorl of reduced filiform tentacles, was reared in aquaria at São Paulo, Brazil. Its medusa was reared and proved to be a new species of medusa of the genus Dipurena, here described as D. reesi. Keys are provided to separate this from other known species, and some observations on the biology of the species are made.
MARSHALL, A. J.; SERVENTY, D. L.
doi: 10.1111/j.1096-3642.1956.tb00484.xpmid: N/A
1 The Short‐tailed Shearwater, Puffinus tenuirostris, migrates annually with remarkable constancy between its southern Australian breeding islands and the north Pacific and Arctic Oceans. The regularity of its southern landfall (in late September) and egg‐laying (during the period November 19 to 21 and the following twelve days) facilitates its commercial exploitation in the Tasmanian “mutton‐birding” industry. 2 The species is highly exceptional in that it breeds in the warmer of the two regions between which it oscillates. It arrives in the breeding area and remains there during the period of surface swarming of the euphausian plankton on which it mainly feeds. 3 Gametogenesis almost certainly begins in the northern hemisphere and this and the nuptial migrations are perhaps initiated by decreasing daylengths. The males possess bunched spermatozoa on arrival at the breeding islands. Individuals “home” to the same nesting site each year. Spermatogenesis then proceeds slowly, and oogenesis steadily, whilst nest‐burrows are renovated and a noisy nocturnal display occurs. Fertilization perhaps takes place ashore after which there is a pre‐laying exodus lasting about three weeks. During this absence at sea the single large egg (about 16 per cent of the female's body weight) matures and the flocks then return for the laying period. 4 The males take the first incubation shift and fast of eleven to fourteen days while the females go back to sea. At initial landfall, and at the time of egg‐laying, both sexes contained abundant depot fat. After their incubation fast the males are relatively lean. The incoming females, on the other hand, are fat. This alternation of fat deposition at sea, and utilization ashore continues during the incubation period of fifty‐three to fifty‐five days. 5 Only one egg is laid per year. Out of season, or even out of phase, breeding is unknown. 6 The seminiferous tubules are already in a state of lipoidal and cholesterol‐positive metamorphosis at the time of egg‐laying when the males take the first incubation shift. The possibility that the luteinized tubules may be an endocrine organ of the same general nature of the mammalian corpus luteum is discussed. 7 Both parents feed the young but desert them while they are still in the burrows at an age of about three months. The mean desertion date is about mid‐April. Both parents, which are now lean, disappear from the breeding area. About a fortnight after their desertion the fat young leave the burrows and disappear. 8 Migration north by both adults and young occurs while abundant food still remains in the breeding area. Sea temperatures are still higher than at the time of ovulation. The cessation of parental responsibility may be a major factor in the stimulus to contra‐nuptial migration in the adults. This movement takes place with both young and adults, probably as in all birds, in accordance with an innate and traditional pattern of behaviour. The post‐nuptial journey of 5,500 miles between Tasmania and the colder Japanese waters has been covered (as proved by a ringed fledgling) within about a month. 9 Breeding does not begin until the birds are six years of age and so a very considerable non‐breeding population exists. These immature birds also undergo annual migrations and partial gametogenesis, some individuals producing a few spermatozoa. 10 A remarkable adaptation to the exacting demands of lengthy migration is shown in the division of the post‐nuptial moult into two phases. The moult of head and body takes place at the breeding site but that of the wings and tail is delayed until the relatively sedentary phase in northern waters.
doi: 10.1111/j.1096-3642.1956.tb00485.xpmid: N/A
1 Detailed studies have been made of the structure and function of the stomach in the two protobranchs, Nucula nucleus L. and Nuculana minuta (Müller). 2 The structure of the stomach in the Protobranchia was described and figured, and defined as Stomach Type I. 3 The stomach of the septibranch Cuspidaria cuspidaia (Olivi) was similarly examined, described and figured, and was defined as Stomach Type II. 4 The stomachs of the Protobranchia and Septibranchia were compared and it was noted that there were several common features. Further resemblances were found in the structure of the digestive diverticula, and in the muscular pumping of water by the ctenidium (Nuculana) or by the septum (Cuspidaria). 5 It was concluded that there is a strong suggestion of phylogenetic relationship between the Protobranchia and the Septibranchia. 6 The view, previously stated by Yonge, that there was no justification for linking the Protobranchia and the Arcacea in an order Taxodonta was upheld.
doi: 10.1111/j.1096-3642.1956.tb00486.xpmid: N/A
All the fossil suid material available from the deposits at Sterkfontein, Swartkrans and Kromdraai has been examined. Only the two species previously described by Broom occur: Tapinochoerus meadowsi (Broom) at Sterkfontein and Swartkrans as well as at the nearby deposit of Bolt's Farm, and Phacochoerus antiquus Broom at Swartkrans and Kromdraai.
doi: 10.1111/j.1096-3642.1956.tb00487.xpmid: N/A
The wings of Chaeteessa are described and the condition of venation commented on. Venation is primitive and blattid‐like.
doi: 10.1111/j.1096-3642.1956.tb00488.xpmid: N/A
1 A new species of Clariallabes is described; this species represents the first record of the genus in East Africa. 2 The apparently neotenic characters of Cl. Petricola are discussed and compared with the larval, post‐larval and juvenile characters of three Clarias species. 3 Hypotheses regarding the adaptive value of neoteny in Clariallabes are considered. 4 It is suggested that the “genus”Clariallabes may be of polyphyletic origin.
doi: 10.1111/j.1096-3642.1956.tb00489.xpmid: N/A
The structure of the capsule of Urosalpinx is described and discussed in relation to the normal hatching process.
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