32 EINAR LÖNNBERG, ANATOMICAL NOTES ON EAST AFRICAN MAMMALS. 



It is difficult to prove such a thing, but the possibility does not appear to be ex- 

 cluded. There is, however, another great resemblance between the ma le organ of the 

 Horses and Rhinoceroses and that is that both are provided with a deep groove 

 (fossa glandis) at the truncate end of the glans, and from this groove the processus 

 urethrce projects. The latter has in the Rhinoceroses a more complicated shape with 

 its mushroom-like dilatation at the apex and the thickness of its peduncle etc, but 

 there appears to be no doubt about the homology. 



Considering all there is such a great agreement in shape and structure between 

 the male organs of the families RhinocerotidaB, Tapiridce, and Equidce that they evi- 

 dently can be derived from a common type which ought to have been thick and 

 truncate, provided with a terminal fossa or groove from the bottom of which an 

 urethral appendage probably arose, and with a pair of lateral lobes at the base of the 

 glans. There is thus an equal conformity in the Perissodactyline series as that which 

 has been proved before in the Artiodactyline with regard to this organ. 



