OVIDUCT OF TOETOISE. 



715 



Fig. 353. 



(2023.) Two retractor muscles, derived from the pelvis, and extending 

 along the under surface of the penis quite to its extremity, fold the 

 whole organ back into the cloaca, where it lies concealed when not 

 in use. 



(2024.) In the Crocodiles and higher Saurians the penis in its struc- 

 ture resembles that of the Tortoise ; and instead of a urethra, there 

 is merely a deep groove traversing the upper surface of the organ, along 

 which the semen trickles out of the cloaca. 



(2025.) Throughout all the 

 Reptile families the organiza- 

 tion of the female generative 

 system is so extremely similar, 

 that one example will be abun- 

 dantly sufficient for our purpose, 

 the same description, in fact, 

 being equally applicable to the 

 Saurian, the Chelonian, and the 

 Ophidian orders. The ovaries 

 occupy their ordinary position 

 in the lumbar region of the ab- 

 domen, where they are attached 

 on each side of the vertebral 

 column by a broad fold of peri- 

 toneum: their structure is in 

 all essential points precisely si- 

 milar to those of the Amphibia ; 

 but, owing to the increased pro- 

 portionate size of the individual 

 ova formed by their vascular 

 membrane, they resemble a 

 string of beads, or assume some- 

 what of a racemose appearance. 

 The oviducts are long and flex- 

 uous ; they commence by a wide 

 orifice (fig. 353, 6 M), by which 

 the germs are taken up from the ruptured ovisacs of the ovaria in the 

 same way as those of Mammalia are seized by the fimbriated extremities 

 of the Fallopian tubes. The first portion of the oviduct is thin and 

 intestiniform ; but lower down, where the investments of the egg are 

 formed, its walls become thicker, and assume a glandular character 

 (n, o, p) ; they finally open into the cloaca ; and the mode of their ter- 

 mination in the Tortoise is exhibited in the accompanying figure, where 

 M, m, e M indicate the terminal portion of the right oviduct laid open, 

 the left (a M, b M) being shown through its entire length. 



(2026.) The formation of the egg and the development of the embryo 



Oviduct and ovum of female Tortoise. 

 (After Bojanus.) 



