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 Lemuroidea 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 preputium 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 preputium 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). 
