Class 5. Aves. 



449 



and fairly constant. On account of tlie size of the eggs the Graafian 

 follicles project from the surface of the ovary^ giving it a racemose 

 appearance. The left oviduct (Miillerian duct), also, is alone 

 well-developed, though a rudiment of the right may be present; 

 during the breeding season the oviduct is long and wide, at other 



Fig. 376. 



Fig. 377. 



Fig. 376. Reproductive organs of a Hen. 

 d rectum, I oviduct, ov ovary, t funnel, u uterus. — 

 Orig. 



Fig. 377. Reproductive organs (and 

 ureter) of a Cock; rectum turned to one side to 

 show the place where the ureters and vasa def erentia 

 open into the cloaca, a anus, h testis, n epididymis, 

 s vas deferens, ur ureter. — Orig. 



times it is a narrow tube opening, by a large funnel, into the 

 body-cavity ; not far from the opening into the cloaca it widens out 

 to form the uterus, where the shell is secreted. The testes, 

 both of which are well developed (although sometimes the left is 

 larger), lie in front of the kidneys; the vasa def erentia, each of which 

 arises from a small epididymis, have a convoluted course, and open 

 separately into the cloaca, usually on small papillae. The testes are 

 very small, except at the breeding season, when they attain a 

 considerable size ; this holds also for the ovaries. A definite penis 

 occurs only in the males of a small number, in Struthious Birds, 

 Ducks, and some others; in the rest it is rudimentary or absent. 



G G 



