VI. FURTHER NOTES ON THE SPONGES 

 OF LAKE BAIKAL. 



By N. Annandai^k, D.Sc, F.A.S.B., Superintendent, 

 Indian Museum. 



(Plate IX). 



In a paper recently published ^ but written some little time 

 ago, I expressed the opinion, tentatively, that the characteristic 

 sponges of Lake Baikal belonged to the subfamily Chalininae 

 and should probably be assigned to the genus Veluspa, Miklucho- 

 Macla}'. At the time I had had, as I pointed out, no opportunity 

 of comparing specimens from the Siberian lake with marine 

 Haploscleridae. This was still the case at the end of 1912 when I 

 was preparing my report on the sponges of the Lake of Tiberias ; * 

 but within the last few months I have been able, thanks ver}^ 

 largely to the rearrangement of the collection of marine inverte- 

 brates in the Indian Museum carried out by Mr. S. W. Kemp, to 

 examine a considerable number of marine Monaxon sponges from 

 different parts of the world. The result has been to confirm my 

 more important contention, that certain of the Baikal sponges were 

 Chalininae; but I find that I was not justified in re-uniting 

 Dybowski's genus Liihomirskia with the older genus Veluspa, from 

 which he separated it in 1879, or in asserting that all the sponges 

 of the lake (with the exception of those belonging to the Spongillid 

 genera Spongilla and Ephydatia) were congeneric. It becomes neces- 

 sary, therefore, to reconsider the generic portion of the species 

 examined, and this will render it possible to discuss their geogra- 

 phical significance. 



The precise systematic position of the sponges that constitute 

 one of the most characteristic features of the fauna of Lake Bai- 

 kal is not only a problem of considerable difficulty, but also one of 

 great geographical interest, Most authorities on the Spongillidae 

 have treated these sponges as a subfamih^ thereof, or merely as a 

 highly specialized genus allied to the African Potamolepis and the 

 South American Uruguava. It is noteworthy that none of those 

 who have hitherto treated in a comprehensive manner of the 

 Spongillidae as a whole have had before them collections from 

 Lake Baikal. Thanks to the authorities of the Zoological Museum 

 of the Imperial Academy of Sciences in St. Petersburg I have been 

 more fortunate in this respect, in that I have been able to examine 



1 Ann. Miis. Zool. Ac. Sci. St. Petersb. XVIII, p. 96 (1913). 

 * Joitrn. As .Soc. Bengal, 1913, p. 77. 



