588 



DR. W. A. CUNNINGTON ON THE 



district fiom which they come is some 200 kilometres or more 

 east of the lake, and that they show East African rather than 

 Tanganyikan affinities. 



The last of the forms enumerated — Potamolepis weli7ieri — was 

 established by Moore (137, p. 323), and regarded by him as peculiar 

 to Ta.nganyika. Moore explains that a small specimen of this 

 sponge was dredged in the lake from great depths during his 

 second expedition *. It has never been adequately examined and 

 described, but Weltner expressed the opinion that it was a 

 distinct species, with a framework very similar to that of SpoQi- 

 gilla hohmii. It was accordingly given the specific name weltneri 

 and placed provisionally in the genus Potamolepis. Kiikpatrick, 

 w^ho has also examined some of the material, exj)resses the view 

 that these two species may possibly be synonymous (105, p. 222). 

 It is perhaps well to leave the m.atter suh judice. particnlarly as no 

 further supply of material has been forthcoming to aid in deciding 

 this point. Moore's comparison of the spicules of this sponge 

 with those of the genus llenieva (which he misquotes Beit.ieria''^) 

 does not strengthen his case. Instead of being "the old fossil 

 genus" {loc. cit. pp. 331 : 354) it would be more accurately de- 

 scribed as the recent marine and brackish-water genus — although 

 fossil re})resentatives also exist in the tertiary stiata. In con- 

 clusion it may be stated that despite the suggested i-esemblance of 

 the spicules of Potamolepis weltne^^i to those of Remiera, the 

 sponge fauna of Tanganyika consists essentially of fresh-water 

 and not marine types, although the foi-ms inhabiting the lake are 

 peculiar to its waters. 



Protozoa. 



It is to be regretted that the Protozoa of Tanganyika have not 

 yet been investigated. There are, it is true, a few species to 

 record, but these are principally forms belonging to the Phyto- 

 llagellata, which are enumerated in th.e report on the Algse of my 

 expedition (200). This is the more unfortunate, since a good deal 

 of information on this group is forthcoming respecting Victoria 

 Nyanza and Nyasa, although much is probably unknown. There 

 is no I'eason to suppose that such a maiked disproportion really 

 exists between the Protozoan fauna of Tanganyika and those of 

 the two other big lakes; indeed, the evidence afforded by many 

 groups of animals suggests that Tanganyika is likely to lead the 

 way with a larger and more unusual assemblage of species. An 

 examination by a pi-otozoologist of the extensive series of tow- 

 nettings and other suitable material which I brought from the 

 lake should go some way towards determining this point, and it 

 is to be hoped that this will be carried out in the near future 

 From Albert Nyanza there are a few forms recorded among th^ 



* It maj' be mentioned in this connection tliat the species obtained by Moore's 

 first expedition were, tbrou^b some misunderstanding, said by Evans to Lave come 

 from a deptli of 350 fatboms (82, p. 471). Moore bimself states (127, p. 405) tbat 

 on tbis expedition 1200 feet (200 fatboms) was tbe greatest deptb at wbicb be was 

 able to dredge. Tbese sponges are not in reality deep-water forms, for, during tbe 

 tbird expedition, 1 found tbem living in quite ibaliow water at tbe lake margiri 



