472 



COMPARATIVE ANATOMY 



munication with the body-cavity and cloaca. A vesicula serninalis 

 may be present on the urinogenital duct (p. 457). 



Hermaphroditism occasionally occurs in the Anura ; only 

 one case (Triton t^niatus) is known amongst Urodeles. A body 

 attached to the anterior end of the testis (" Bidder's organ ") 

 in various species of Toads contains cells quite similar to young 

 ova, and a similar body is present at the anterior end of the ovary, 

 the cells in which are, however, incapable of ripening. In the 

 males of Pelobates, Bufo, and Ran a temporaria, ova are at times 

 developed within the substance of the testis (hermaphrodite gland 

 or ovotestis), and one testis may even be replaced by a rudimentary 



FIG. 355. TESTIS AND ANTERIOR END OF KIDNEY OF Raiia esculenta. 

 (Semidiagrammatic. ) 



Ho, testis ; L, longitudinal canal of the testicular network, from which the iiiter- 

 renal network (C, C) arises ; JV, kidney; q, q, transverse canals of the testi- 

 cular network, which give rise to blind processes at f t ; Ur, urinogenital 

 duct. 



ovary : in Rana, the Miillerian duct may then be as well developed 

 as in the female. 



The ovaries of Urodela are always formed on a common plan : 

 each consists of an elongated, closed tube, with a continuous lumen. 

 In Anura, on the contrary, the ovarian sac (Fig. 356) is divided up 

 into a longitudinal row of numerous (3 to 20) separate pockets or 

 chambers, on the walls of which the ova are developed and project 

 into the cavity, eventually breaking through into the ccelome. 

 The oviducts open far forwards into the body-cavity by funnel- 

 shaped apertures ; they take a tolerably straight course along the 

 outer borders of the kidneys to the cloaca in young animals, but 

 become greatly convoluted and glandular later. A short distance 



