292 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Unity of Gnathostome Type.* — Howard Ayers assumes a hypo- 

 thetical group (Haeckel's Prospondylia) as the stock from which the 

 Leptocardia and the Archicrania both arose. From the latter are de- 

 veloped all the Craniate forms, which are usually classified in two main 

 divisions, the Cyclostomata and the Gnathostomata. But in 1894 the 

 author showed that the so-called tongue apparatus of the Cyclostomes, 

 particularly the Myxinoids, was developed by a transformation of the 

 maxillo-mandibular apparatus of some Gnathostome ancestor. Other 

 reasons strengthen his conviction that all the Craniata are Gnatho- 

 stomes, and that the only living Acraniate is Arnphioxus. 



Ichthyological Notes.f — T. Wemyss Fulton describes two young 

 conger-eels in the Leptocephalus-stage from the Moray Firth — rarities 

 in British seas ; a larval Fierasfer from the North Sea — another rarity ; 

 a sting-ray (Trygon pastinacea) from the Dornoch Firth — a • very rare 

 fish in Scottish waters ; and a pilchard from the Moray Firth which is 

 equally rare. He notes that the sprat shed at least 5000 eggs, but it is 

 one of the least fecund of fishes, and, so far as is known, the least 

 fecund of all fishes whose eggs are. pelagic. He reports an albino plaice 

 in which pigment was almost entirely absent ; it lived for about a year, 

 and differed from its neighbours in clinging to the side of the hatching- 

 box close to the surface of the water. A reversed action of the gill- 

 cover in plaice is also recorded. 



Vendaces of British Lakes. J — C.T.Regan describes Goregonus 

 vandesius from Lochmaben, and G. gracilior sp. n. from Derwentwater 

 and Bassenthwaite lakes, Cumberland. The former, which by some 

 authors is united with C. albula of Northern Europe, can be separated 

 from its nearest continental allies by several distinctive features. G 

 gracilior, though closely allied to the Lochmaben form, is by no means 

 identical with it. 



South American Cichlidae.§ — C. T. Regan completes his account of 

 the American Cichlidse in the British Museum. The paper consists of 

 a revision of the genera Gichla, ChMobranchus, and Ghmtobranchopsis, 

 and includes a synopsis of all the genera of the family, together with a 

 discussion of their distribution and probable relationships. 



Dentition of Characinoid Genus Piabuca.|| — W. S. Rowntree calls 

 attention to certain interesting features in the dentition of this genus. 

 The teeth are of singular beauty, being arranged in uniform series, and 

 having spatulate crescentic crowns edged with minute gold-tipped serra- 

 tions. Two points of some significance which have not been appreciated 

 by other observers, are the existence of additional teeth not in series 

 with the others, and the presence of teeth in the maxilla as well as in 

 the premaxilla. In respect of this latter condition, Piabuca occupies a 

 somewhat central position in the Characinidse, in which family all inter- 

 mediate stages are now shown to exist between the presumably primitive 



* Amer. Nat., xl., (1906) pp. 75-94. 



t Fishery Board for Scotland, Report 22, part iii. (1904) pp. 281-7 (1 pi.). 



\ Ann. Nat. Hist., xcviii. (1906) pp. 180-2 (1 pi.). 



§ Tom. cit., pp. 230-9. || Torn, cit., pp. 240-3 (1 fig.). 



