60 STUDIES IN COMPARATIVE ANATOMY. 



fold of peritoneum. In the last part of its course it lies upon 

 the upper surface of the bladder. Here it dilates into an 

 ampulla two inches long, which is closely connected with its 

 fellow. It finally unites with the efferent duct of the vesicula 

 seminalis of the same side to form a common ejaculatory duct^ 

 which opens into the urethra. 



Vesicul.e Seminales. 



These have been figured by Camper (pi. v. fig. 1), and described 

 by Cuvier. Each is six inches long by one and a half in diameter, 

 and lined internally by a thick membrane thrown into decussat- 

 ing folds, which become longitudinal towards the urethral end 

 of the sac. A large transverse fold apparently divides the cavity 

 into two compartments. Each vesicula is invested by a thick 

 layer of muscular fibres, continuous with that which surrounds 

 the membranous part of the urethra and the prostate glands. 



Prostate Glands. 



These are four in number, two on each side, and of small size, 

 the outer ones being the larger. Each gland opens into the 

 urethra by a single and separate duct. 



Cowper's Glands. 



These are, as usual, two in number. Each is oval, flattened, 

 and measures two and a half inches by two. The excretory duct 

 is three inches long, and traverses the spongy body, opening 

 separately on the floor of the bulbous portion of the urethra. 



Male Urethra. 



The membranous portion is eight inches long. It is invested 

 by a continuous layer of transverse muscular fibres a quarter of 

 an inch thick. Towards the neck of the bladder these become 

 oblique and continuous with those which invest the prostate 

 glands and the vesiculse seminales. An extension of the erectile 

 tissue of the bulb surrounds this part of the urethra, thinning 

 off gradually towards the neck of the bladder. The orifices of 



