PLACENTAL GENERATIVE ORGANS FEMALE. 



835 



dered a most formidable-looking apparatus, the object of which it is not 

 easy to conjecture, although, as an instrument of excitement, no one will 

 be disposed to deny its efficiency. 



(2477.) Thus, in the Guinea-pig tribe (Cavia, Illig.), the penis is 

 strengthened by a flat bone that reaches forward as far as the extremity 

 of the gland beneath which is the termination of the urethra ; but 

 behind and below the orifice of this canal is the opening of a pouch, 

 wherein are lodged two long horny spikes. When the member is erect, 

 the pouch alluded to becomes everted, and the spikes (fig, 420, d) are 

 protruded externally to 



a considerable length. Fig. 420. 



Both the erected pouch 

 (b) and the entire sur- 

 face of the glans are, 

 moreover, covered dense- 

 ly with sharp spines or 

 booklets ; and as though 

 even all this were not 

 sufficient to produce the 

 needful irritation, still 

 further back there are, 

 in some species, two 

 sharp and strong horny Penis of the Agouti. 



saws (c c) appended to 



the sides of the organ. From this terrible armature of the male Cavies, 

 it would be only natural to expect some corresponding peculiarity in the 

 female parts ; but, however inexplicable it may appear, the female vagina 

 offers no uncommon structure. 



(2478.) We have, in the last place, to examine the generative system 

 of the female placental Mammalia, and thus to trace the development of 

 this important system to its most complete and highest form. 



(2479.) In the Marsupialia, as the reader will remember, there were 

 still two distinct uteri, that were obviously the representatives of the 

 oviducts of the Oviparous classes. In the Human female, on the con- 

 trary, the uterus is a single central viscus, into which the germs derived 

 from the ovaria are introduced through the two " Fallopian tubes" as 

 the oviducts are now designated ; but we shall soon see that the vivipa- 

 rous Mammals offer in the anatomical structure of the generative system 

 of the female so many intermediate gradations of form, that we are 

 almost insensibly conducted even from the divided uteri of the Ornitho- 

 rhynchus up to the most elevated and concentrated condition that the 

 uterine apparatus ultimately attains in our own species. 



(2480.) In the female Eabbit, for example, we have a placental 

 Mammal that in every part of the organization of its reproductive organs 

 testifies its near affinity to the Marsupial type. The ovaria (fig. 421, k, I), 



3n2 



