MB. G. A. BOULENGER ON A COLLECTION 

 IV. Lake Rudolf 1 . 



Cichlid^:. 



1. Tilapia nilotica Cuv. 



2. ,, tristrami Gthr. 



Silurid^e. 



3. Synodontis schal Bl. Schu. 



4. „ smithii Gthr. 



Cyprinidjk. 



5. Barbus, sp. 



Characinidjs. 



6. Citharinus geoffroyi Cuv. 



7. Alestes rueppellii Gthr. 



8. Distichodus rudolphi Gthr. 



POLYPTERID^E. 



9. Polypteras senegalus Cuv. 



The fishes of Lake Nyassa are, with two exceptions, specifically distinct from those 

 of the Nile, as pointed out by Dr. Giinther 2 , while seven out of forty-three species 

 represented in Lake Tanganyika occur both in the Nile and in the rivers flowing into 

 the Atlantic. And as the Mormyridce, which furnish the two species common to 

 Nyassa and the Nile 3 , have not yet been recorded from Tanganyika, while, with the 

 exception of a small stream-Siluroid, not One of the species described from the former 

 lake has been rediscovered in the latter, it follows that, although similar in general 

 character, the fish-fauna of the two lakes shows no trace of community so far as 

 specific forms are concerned, as might have been expected from the absence of direct 

 communication between them. 



Before concluding these prefatory remarks, I wish to express my thanks to 

 Messrs. J. H. Gardiner and J. Green for their kind assistance in supplying me with 

 sciagraphs of the new fishes, which, supplementing the skeletons prepared by 

 Mr. Groenvold, have enabled me to add some notes on the osteological characters of 

 the genera described as new. 



Sekkanidj;. 

 1. Lates microlepis, sp. n. (Plate I. fig. 1.) 



Body elongate, its depth 3| times in the total length. Length of head 3 times in 

 total length ; upper profile nearly straight ; diameter of eye equal to length of snout, 

 3f times in length of head ; lower jaw projecting ; maxillary extending to below centre 

 of eye, the width of its distal extremity not quite half diameter of eye ; prse- and 

 suborbitals finely serrated ; cheeks, opercles, -and occiput covered with small scales ; 

 praeopercular border forming nearly a right angle, finely toothed on its vertical limb, 

 with two or three widely-separated spines on its lower limb, and with one or two very 



1 Giinther, P. Z. S. 1896, p. 217. 2 ' Study of Fishes,' p. 230. 



3 If, as seems probable, the distinction between Mormyrops zambanenje and M. anguilloides should not be 

 maintained. On the other hand, the Nilotic specimens referred to Mormyrus discorhynchiis may prove to 

 be specifically separable. Lake Tanganyika might thus ultimately possess no species of fish in common with 

 the Nile. 



