588 ANATOMY OF VERTEBRATES. 



at the termination, f, where the egg-shell is secreted, the 

 membrane is vascular, and thrown into broad irregular ruga?, 

 which are continued as far as its termination, n, in the cloaca. 

 The ureter, e, opens behind the oviduct, a : the allantoic bladder, 

 b, and rectum, m, in front. 



In Crocodilia the ovaria are more advanced in position, and more 

 compact in form and structure, presenting, in the unexcited state, 

 a surface granulated by minute ovisacs. The abdominal orifice of 

 the oviduct has an entire margin; the duct maintains a more 

 uniform diameter, and sooner gets upon the edge of the supporting 

 fold of peritoneum than in Chelonia. The lining membrane of 

 the hind part of the oviduct is puckered up into close-set undu- 

 lating transverse rugae : but these subside gradually toward the 

 terminal shell-forming segment, where the membrane shows minute 

 longitudinal puckerings. The outlet projects into the cloaca. 

 The clitoris arises by two crura, and is impressed by a longitudinal 

 groove. 



Of parts in female Reptiles accessory to generation, the most 

 remarkable are the temporary tegumentary pouches on the back 

 of the female Pipa, fig. 367, B, C, which, receiving the impregnated 

 ova, retain the young until the metamorphosis is complete. In 

 Nototrema and Opisthodelphys there is a large single pouch in 

 the middle of the back, with the entrance above the vent. It 

 serves for the reception of the ova, which are hatched therein. 

 This pouch is peculiar to the female, which attains nearly to its 

 full size before the pouch is developed. After the reception of 

 the ova, it extends nearly over the whole back of the animal, 

 whilst it is shrunk and scarcely visible when the season of pro- 

 pagation has passed. 



