148 Records of the Indian Museum. [Voi,. X, 19 14.] 



devoid of reproductive bodies that would be easily transported by- 

 external agencies, affords, in any case, strong support for the view 

 that the fauna of the lake includes a real marine element derived 

 from northern waters ; while the prolific evolution of species in 

 the apparently endemic genus Baikalospongia is exactly- parallel 

 to the state of affairs found in the Amphipoda ' and the Gastro- 

 poda * of the lake and points to isolation for a considerable period. 



' Dybowski, " Beitr. der in dem Baikal- See vorkommenden . . . Gammari- 

 den, " Hovae Soc. Ent. Russ. X (1874). 



2 Lindholin, Wiss. Ergehii. Zool. Exp. Baikal-See, Die Mollitskeu C1909). 



ADDENDUM. 



When this paper went to the press I had not seen Topsent's 

 paper on the classification of the Halichondrine sponges on larval 

 characters {Arch. Zool. (5) VII, pp. i-xv). He points out (p. xiv) 

 that the larvae of the Haploscleridae {s.s.) possess a coloured 

 cap or collar at the posterior, non-ciliated extremity. — April 2^th, 

 1914. 



