1901.] ANATOMY or COGIA BREVICEPS. 127 



which is continuous laterally with the longitudinal septa above 

 referred to. 



The fascicles in this region are, then, attached only to the septa, 

 and are independent of the crus c. spougiosi. 



The erector penis (Er.) is a plano-convex muscle, enclosing the 

 crus corporis cavernosi of its side. It is shorter than the acce- 

 lerator, being only 4 inches in length. It is made up of large 

 fascicles, the direction of which varies in different parts of its 

 extent ; in fact, they radiate from a small circular tendinous patch 

 on the outer svirface near the binder end of the muscle (t). 



From this area the most anterior fascicles pass directly forwards 

 to be inserted in the corpus cavernosum ; those in the middle of the 

 series pass directly inwards, and the most posterior ones backwards 

 and inwards. The opposite ends of these fascicles are attached to 

 the fibrous tunic of the crus penis. 



A small separate muscle (PI. XI. figs. 24, 25, m.) arises from 

 this tendinous patch, the fibres of which pass backwards and enter 

 the sphincter ani. It seems probable that this represents the muscle 

 marked " a" in Struthers's figures 13 & 14, arising from the hinder 

 end of the pelvic bone, and which he terms the " caudal muscular 

 mass.'^ 



Prof. Turner found no muscle attached to the hinder end of the 

 pelvic bone in the Grampus. 



The retractor penis {Re.) is, as usual, a double muscle, though the 

 two are closely bound together. Each is band-like, and measured 

 -| inch across and ^ inch in thickness. They are attached at one 

 end to the corpus cavernosum, immediately proximal to the insertion 

 of the penial sheath ; posteriorly they lie in the groove between 

 the two accelerators, and finally burrow upwards between the 

 anterior and posterior moieties of these muscles, to gain the dorsal 

 surface. They then pass behind the posterior margin of the 

 " pelvic fascia " and enter the muscle surrounding the rectum 

 (PL XI. fig. 25). 



The retractors are 13 inches long, and they lie quite loosely 

 separated from the penis, except at the two ends. 



The upper surface of the accelerator muscles is covered by a 

 tough, inextensible membrane, the margins of which had been cut. 

 But from its relation to the muscles and other structures, it 

 appears to be the " pelvic fascia" (PI. XI. fig. 24, Z.). Anteriorly, it 

 bears on its under surface the two seminal ducts ; on each side is 

 seen an artery {ar.) — dipping downwards below it — the pudic 

 artery, and posteriorly it is slightly reflected on to the rectum. 



A short distance behind the anterior, cut edge is a depression 

 caused by the origin, from its under surface, of a couple of muscles, 

 which pass forwards, diverge, and embrace the urethra, just above 

 the prostate gland. The muscle-fibres enter the muscular coat of 

 the urethra on its anterior face (Pi. XI. fig. 25, C.u.). This almost 

 circular muscle appears to be the " compressor urethras" ( = com- 

 pressor prostatae of Turner). In the Grampus, however, it is 

 rather a sheet of muscle-fibres, covering the whole of the upper 



