Genito-nrinarij Ajjparahts of the Male Porpoise. 127 



distinct from the inter-pubic ligament or membrane. As a 

 consequence, the transverse perineal muscles, viz., the super- 

 ficial and the deep or compressor urethrce, were not developed, 

 and the membranous portion of the urethra was not defined 

 as a distinct urethral segment. 



A powerful bilateral retractor muscle, of pinkish colour, 

 and 15 cm. in length, came into view through the central 

 part of the perineum, between the anus and the bulb of the 

 corpus spongiosum. It consisted of two portions, each of 

 which arose in association with the strong fascia investing 

 the longitudinal muscles on the dorsal aspect of the rectum. 

 Each half passed ventrally across the lateral aspect of the 

 rectum, and having reached its ventral aspect, the two bands 

 approached each other mesially, and thereafter continued 

 forwards on the ventral aspect of the penis, accommodating 

 themselves to the bulbs and the penile circle. At first these 

 bands were rounded, but as they passed forwards they 

 became flattened, and finally were inserted into the strong 

 fascia investing the penis at a point close to the reflection 

 of the preputial mucous membrane. Microscopic examina- 

 tion showed that these muscles consisted of non-striped or 

 involuntary fibres. 



The Urethra presented very distinct j^'t^ostatic and spongy 

 portions, but it could not be said to possess a membranous 

 part in the sense in which this term is used in human 

 anatomy. 



(a) Prostatic urethra. On slitting open this part of the 

 urethra, a distinct verumontanum was exposed. It pro- 

 jected from the rectal or dorsal aspect of the urethra, and 

 on each side of this elevation there was a longitudinal groove 

 or fornix, the right and left prostatic sinuses. At its hinder 

 end, the verumontanum presented an abrupt free face, upon 

 which four openings were visible. Of these, two were situ- 

 ated on the ventral aspect, and the other two distinct orifices, 

 which were also placed right and left of the mesial plane, 

 lay towards the dorsal aspect of the free face of the veru- 

 montanum. Each of the ventral orifices was shaped like a 

 transverse slit, and could easily be occluded by the pressure 

 of its two lips against each other. These orifices formed the 

 VOL. XV. K 



