COPULATORY ORGANS 



491 



FIG. 369. CONTINUATION OP FIG. 368. 



A, Marsupial (very diagrammatic, for comparison with Fig. 368, C ; the obliter- 

 ated opening of the urinogenital canal into the cloaca is indicated by dotted 

 lines) ; B, Rodent, (Ccelogenys paca) ; C, Ape(Cercopithecus): in most placental 

 Mammals the apex of the penis is not pendulous ; D, Man ; E, Human 

 foetus. 



Additional letterings : a, anus ; at, stalk of allantois ; b, pelvic symphysis ; p, 

 genital prominence which gives rise to the penis or clitoris. 



with the urethra of the penis. The fibrous body is paired, and 

 both it and the walls of the penial urethra are composed of 

 cavernous tissue. Both penis and clitoris are frequently bifurcated 

 at the apex. 



Amongst the Eutheria the penis of Rodents (Fig. 369, B) and 

 Insectivores comes nearest to that of Marsupials. The paired 

 fibrous body (corpus cavernosum) bifurcates proximally to form two 

 crura, which are nearly always attached to the ischia. The opening 



CU 



FIG. 370. A, SEMIDIAGRAMMATIC FIGURE OF THE HUMAN PENIS. (In transverse 

 section and from the side). B, CLITORIS OF A MONKEY (Cebu-i capucinus). 



A, albuginea penis; A 1 , albuginea urethra?; Ccp, corpus cavernosum; Ccu, 

 corpus spongiosum, which gives rise to the glans penis at Gp, and forms an 

 oval enlargement (bulbus) at B ; Gli, clitoris, with its ventral furrow (K), 

 glans (Gc), and prepuce (Pp) ; rd, rd 1 , crura of the corpora cavernosa ; *S Y , 

 sulcus dorsalis penis ; tip, septum between the two corpora cavernosa. 



of the penis-sheath gradually becomes further separated from the 

 anus, and is situated more on the ventral side of the body (cf. B 

 and c), the penis itself lying horizontally along the abdomen. 

 In Primates the organ becomes more or less free from the body- 

 wall, and either its distal end (Apes, c), or the whole of it (Man, D), 

 is pendulous, and the sheath forms a double tube-like investment 

 over the glans the foreskin or prepuce, enclosing sebaceous 

 (preputial) glands. 



In the course of development, the penis of Marsupials and 



