ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 173 



atics being present, and absorption is entirely carried on by the veins. 

 In the lamprey there is present in the sub-mucosa a kind of cavernous 

 tissue, which seems to play the part in absorption taken higher up by 

 the network of lymphatics. Somewhat similar conditions exist in Elas- 

 mobraucbs, but here the arrangement of the veins has undergone certain 

 complications. 



Origin of Colour in Animals.* — G. E. H. Barrett-Hamilton returns 

 to the discussion of the theory previously expressed by him, that in the 

 animal kingdom generally the splendour of the nuptial tints in many 

 animals may be ascribed, in origin at least, to pathological changes 

 brought about by the effort to produce as large an amount as possible of 

 tbe genital products. In its first statement his theory was based chiefly 

 on the colouring of the Salmonoid genus Oncorhynchus. In the present 

 paper, he endeavours to show that the Fishery Board Investigations on 

 the life-history of Salmo salar also support his theory, and reviews these 

 investigations from his own standpoint. 



Distribution of Siluroids.j — Franz Poche points out that Boulenger's 

 statement that the genus Pimelodus has no African representatives is 

 incorrect, for P. guttatus from the Cameroons shows that this South 

 American genus does occur in Africa. He also emphasises the fact that 

 still another South American Siluroid genus is represented in Africa, 

 namely Auchenipterus, for A. (Laimumena) horhonica from Madagascar 

 and Bourbon (?) is closely related to the American A. nodosa. This 

 remarkable affinity between the fresh-water fishes of the Ethiopian and 

 Neotropical regions is emphasised by the occurrence of the genus Goty- 

 lopus (family Gobiidae) in Madagascar, Keuniou, and in Central and 

 South America, but nowhere else. In the same connection the distribu- 

 tion of the snake genera Boa and Corallus should be noticed. 



Distribution of Anoplopterus platychir.J — Franz Poche publishes 

 a note on the distribution of this remarkable Siluroid fish. The species 

 was erected by Giinther for a specimen labelled Sierra Leone, but 

 Boulenger, having found that two Siluroids from northern Nyassaland 

 fall into this species, suggested that the locality Sierra Leone on 

 Gunther's specimens was an error, for he considered it very unlikely 

 that so highly specialised a form should occur in two such distant 

 regions of Africa. But Poche points out that whatever the locality of 

 Gunther's specimens, there can be no doubt that the species does occur 

 in West Africa, for it is described by Eochebruue as tolerably common 

 in Senegal and Senecjambia. Poche believes that it will be found to 

 occur across the whole breadth of the African continent. 



Periodic Growth of Fish-Scales. § —J. Stuart Thomson points out 

 in an interesting preliminary note on this subject, that in Gadoid and 

 Pleuronectid fishes there is distinct evidence of periods of growth. The 

 scale growth is accelerated during the warmer season of the year ; but 

 diminished during the colder season in such a methodic manner as to 

 cause the formation of annual rings. The lines of growth oq the scale 

 surface are comparatively widely separated in that portion formed during 



* Ann. Mag. Nat. Hist., ix. (1902) pp. 106-20. 



t Zool. Anzeig , xxiv. 1 1901) pp. 569-71. J Op. cit, xxv. (1902) pp. 121-2. 



§ Journ. Mar. Biol. Ass., vi. (1902) pp. 373-5 (1 pi.). 



