250 FEESHWATEK SPONGES COLLECTED IN SCOTLAND. 



little doubt that it exists in other British lakes as well as in Loch Baa. 

 In any case, the freshwater sponges, being verj easily carried abroad in 

 the form of gemmules, are,, like the Phylactolsematous Polyzoa with their 

 statoblasts, too widely distributed as a rule, although some species are 

 strangely local, to afford a sound basis for argument as to the geological 

 history of any country. In some cases, moreover, environment appears 

 to be a more important feature in their distribution than locality; and 

 we find instances like that of Epliydatia plumosa, which is common in 

 Bombay and of which local races have been found in Mexico and in 

 Lake Tanganyika, while closely allied forms occur in the Malay Peninsula 

 and Australia, but a close two years^ search has failed to discover any ally 

 in Calcutta. 



Although it is in a high degree probable that species other than the 

 two discussed above occur in Scotland, I have been unable to find 

 records that refer certainly to any other than Spongilla lacustris. It is 

 possible, however, that such records exist, for our Indian libraries are 

 naturally incomplete as regards the publications of local societies in 

 Scotland and works confined to the local faunas of Great Britain generally. 

 Weltner * in his list of the known species (1895) does not distinguish 

 Scotland from England and Ireland, and I have not seen any reference 

 to later records from Scotland in any of the usual sources of information 

 on such points. I hope, however, that these notes will be of use, if only 

 they assist in calling attention to the fact that the freshwater fauna of 

 the British Isles is very imperfectly known, a fact strikingly illustrated 

 by Mr. Tate Regan^s f recent paper on the species of Coregonus that 

 occur in the English lakes. The investigations into the fauna of the 

 Scottish lakes undertaken by Sir John Murray and his colleagues are 

 mainly concerned with the plankton ; the bottom fauna has remained 

 almost an untrodden field since Allman carried out the classical researches 

 embodied in his Monograph of the Freshwater Polyzoa (1856). 



* Wiegmann's Arcliiv f. Naturgescli. Ixvi. p. 114, 

 t Ann. & Mag. Nat. Hist. (7) xvii. p. 180, 1906. 



