COPULATORY ORGANS. 329 



out life in the case of the female, while in the male the groove 

 becomes closed to form a canal, and the urethra is considerably 

 lengthened. Three cylindrical bodies, composed of erectile tissue 

 (two lateral corpora cavernosa and a median corpus spon- 

 giosum), become developed in connection with the penis: these 

 are connected with one another by a network of fibrous tissue, 

 and are partially invested by muscles (Fig. 257, Ccp, Ccu\ Corpora 



-Cc/i 



nt' 



FIG. 257. SEMIDIAGRAMMATIC FIGURE OF THE HUMAN PENIS. (A, transverse 

 section ; B, side view ; C, from below. ) 



A, albuginea penis ; A 1 , albuginea urethrse, which gives rise to a septum at Sp ; 

 S, sulcus dorsalis penis ; Ccp, corpus cavernosum ; Ccu, corpus spongiosum, 

 which gives rise to the glans penis at Gp, and forms an oval enlargement (bulbus) 

 at B ; rd, rd 1 , crura of the corpora caVernosa. 



cavernosa are also present in the clitoris, but a corpus spongiosum 

 is wanting. In Marsupials and the higher Mammals the corpora 

 cavernosa diverge at their proximal ends to form two crura (rd, rd 1 ) 

 which are almost always attached to the corresponding ischia. 



In many Mammals a membrane bone (os penis) becomes 

 developed in the septum between the corpora cavernosa (e.g. many 

 Monkeys, Rodents, Bats, Carnivores). In the Seal there is an os 

 clitoridis in the female also. 



