PLATANISTA. 477 



are aberrant vasa efferentia, and the other unbranched cseca may be regarded in the 

 same light. 



Vas deferens. — This passes off from the epididymis at its outer and posterior 

 extremity to reach the body, bending on itself to do so. It leaves the anterior 

 extremity of the tail on a line with the lower end of the testicle along the free 

 margin of the fold of the peritoneum, which stretches across the pelvic portion of 

 the abdominal cavity and connecting the testes. It has the ureter behind it as it 

 leaves the epididymis, and in the mesial line is in close contact with its fellow of 

 the opposite side. Thence it suddenly turns backwards along the side of the con- 

 tracted bladder and is crossed by the ureter immediately above the point of its 

 attachment to that viscus. Beyond that locality it passes downwards and inwards 

 and perforates the wall of the prostatic portion of the urethra about 0*75 inch above 

 the caput gallinaginis to terminate on it as the seminal duct. 



Caput gallinaginis. — This is situated on the back wall of the prostatic portion 

 of the urethra, and the longitudinal ridge from the uvula vescise is continued with 

 it. It depends on the floor of the urethra below it, and has a rather deep recess on 

 either side of it, in which the ducts of the prostate are situated. It is 0*30 inch 

 in length and in breadth, and 0*25 in height. Its extremity is surrounded by a 

 fringe of mucous membrane which seems to assist in closing the two orifices of 

 the seminal ducts, one of which is placed on either side of its free extremity with 

 the sinus pocularis between and rather posterior to them. They are rounded 

 orifices placed on either side of a thin partition, the free end of which expands 

 from before backwards into a somewhat elongatedly rounded membrane with 

 a rather tumid edge, and in the centre of which is the very shallow depression, 

 the sinus pocularis. It is little more than 0*02 inch in depth, and when the 

 two halves of the tumid edge are opposed like lips to the sinus, it cannot be 

 detected. 



Mammary organs. — In the male the mammae are situated 0"30 inch in front 

 of the vent, with an interval between them of 0*25 inch. The nipple is freely exposed 

 on the surface, and is a short rugose cylindrical structure 0*25 inch in diameter, and 

 0-30 inch in height. Its tip is pale yellowish, perforated at the apex by a single 

 orifice and more or less flattened and rugose. The gland is a small honeycombed 

 structure, 0*30 inch long, and 1 inch in diameter, surrounded by a ring of fine 

 muscular fibres derived from the superficial sphincter of the anus. The area around 

 the anus is highly vascular ; the orifice is transverse and the outer skin thrown into 

 numerous cross folds. 



In the female, the nipple is situated at the base of a deep pit, about an inch 

 anterior and external to the anus (PL XXI, fig. 1, m), 0-45 inch in depth, and 0-50 

 inch in longitudinal diameter. The nipple itself is a small conical structure com- 

 pressed laterally, about 0*20 inch in height by 0*30 inch in its longitudinal length, and 

 0-15 broad in its transverse section. It is perforated at its apex by a single orifice 

 that admits the passage of a probe. The canal in question is very short, not more 

 than 0-20 inch in length, but it is very extensile. It commences at the posterior 



