THE URINOGENITAL SYSTEM 195 



cloaca. This points back to a condition which must have 

 existed in the remote ancestors of Man, for a cloaca persists 

 throughout life in Amphibians, Reptiles, and Birds, as well as in 

 the lowest Mammals, which last are on this account called the 

 Monotremata. 



In the further course of development the cavity of the cloaca 

 becomes divided into two, the posterior chamber serving as a 

 prolongation of the rectum, the anterior forming a sinus 

 urinogenitalis, from the anterior wall of which the genital 

 eminence is developed (cf. Fig. 103, G and H). 



EXTERNAL GENITAL ORGANS OF THE FEMALE 



Concerning the external genital apparatus of the female, the 

 labia majora are probably to be regarded as partially developed 

 homologues of the scrotum of the male. Indications of them are 

 found even in the Lernuroidea and the Apes ; but in most Apes it 

 appears that only the lesser system of folds found in women, the 

 labia minora, form the boundary of the genital aperture. The 

 labia minora, which form a strong praeputium and frenulum 

 clitoridis, belong ontogenetically to the genital eminence, and are 

 developed upon its lower surface. They thus fall under a 

 different morphological category from the labia majora. 



The clitoris in Apes is both relatively and absolutely larger 

 than in human beings, and its under surface is furrowed as far as 

 the urinary aperture. This primitive condition is recalled by the 

 occasional condition, due to arrested development of the genital 

 eminence, known as hypospadias. 



In certain branches of the Ethiopian race the females are 

 distinguished by a very slight development of the labia majora 

 and of the mons veneris, and of hair about these parts. On the 

 other hand, among the female Hottentots, a marked hypertrophy 

 of the labia minora and of the prseputium clitoridis is well 

 known, giving rise to what is known among Bushwomen as the 

 "Hottentot apron." [This, however, is most probably due to 

 manipulation, and to the wearing of a split stick with a weight 

 attached.] The vagina appears (as in Apes) smoother, it being 

 less strongly folded than in unmarried Europeans. In Japanese 

 women the labia majora and the mons veneris are feebly developed 

 and but little hairy, and the labia minora seem also to be but 

 slightly developed (Bischoff). 



