Genito-uHnary Apparatus of the Male Porpoise. 123 



Antero-posteriorly (in the direction of the urethra) it 

 measured 4 cm. in length, while in the transverse direction 

 it measured rather more. It did not come into actual con- 

 tact with the neck of the urinary bladder, but left from 3 to 

 5 mm. of the urethra visible in this position, where the vasa 

 deferentia and the uterus masculinus were visible. 



The dorsal surface of the prostate was to some extent 

 separated from the adjacent surface of the rectum by the 

 hinder or blind end of the peritoneal pelvic cavity — the 

 recto-vesical pouch. Nevertheless this aspect of the pros- 

 tate presented a longitudinal shallow groove which 

 corresponded to the wall of the rectum. The anterior or 

 vesical border of this prostatic surface was thick, rounded, 

 and well defined. It resembled a thickened ring, into which 

 the various structures piercing the gland passed. 



The ventral aspect of the prostate was flattened. It lay 

 in close apposition with the hinder part of the strong fibrous 

 membrane connecting the anterior halves of the two pelvic 

 or innominate bones. 



Transversely, the prostate extended so as to occupy the 

 space between these two bones, and its lateral margins were 

 rounded, while the gland as a whole was compressed dorso- 

 ventrally. The hinder or distal end of the gland faded upon 

 the urethra. 



External to the prostate on its dorsal aspect, masses of 

 lymphoid tissue were found along the line of the great 

 vessels, but no glands homologous to Cowper's glands were 

 seen. 



A muscle homologous to the levator ani muscle arose from 

 the posterior three-fourths of the dorsal aspect of the inno- 

 minate bone. It was flat and well developed. Its fibres 

 passed obliquely backwards in the dorsal direction, covering 

 the hinder and dorsal part of the prostate. 



Thereafter they continued their course across the lateral 

 aspect of the rectum. On the dorsal and posterior aspects of 

 the rectum, this muscle fused partly with its fellow and 

 partly with another mass of muscle which arose from the 

 hinder part of the innominate bones, and very probably repre- 

 sents the ischial or hamstring muscles of other Mammalia. 



