612 



COMPARATIVE ANATOMY. 



The generative apparatus of the Amphibia is very similar to that 

 of the Selachii. The ovaries (Fig. 348, A, ov) form lamelke, which 

 project into the abdominal cavity, and vary in size according to the 

 number of the eggs which are being developed. In the Urodela 

 they enclose a cavity, which is broken up into several spaces in the 

 Anura. The Mullerian duct forms the oviduct (od), which com- 

 mences a long way anteriorly, 

 by an infundibular orifice, and 

 which always opens separately 

 into the cloaca. It is generally 

 greatly increased in size at the 

 breeding season; this results in 

 its being thrown into a number 

 of coils. In the oviparous species 

 (Salamandra) the terminal por- 

 tion of the oviduct functions as 

 a uterus. 



The testes are placed in the 

 same region as the ovaries. They 

 either form a compact organ, or 

 consist of a series of larger or 

 smaller (and consequently more 

 numerous) bodies. The latter is 

 the case in many Ccecilias, while 

 in others there are intermediate 

 stages towards the more compact 

 form. A longitudinal collecting 

 duct receives the efferent ducts 

 of the different portions of the 

 testis, and gives off again trans- 

 verse canals, which correspond 

 in number to the primary divi- 

 sions of the kidney and are con- 

 nected with them. The kidney, 

 therefore, is the efferent duct 

 for the sperm, which is passed out 

 through the ureter (secondary 

 arehiuephric duct). In the Anura, 

 the sperm from the testis is 

 passed to the kidney by a net- 

 work of fine canals which are 

 The canals, however, which pass 

 into the kidneys from the longitudinal collecting duct, traverse the 

 kidneys, without being connected with the Malpighian corpuscles, 

 and open directly into the ureter. Bufo is the sole exception ; in it 

 there is a connection between the vasa efferentia and the Malpighian 

 corpuscles. In tho Urodela the anterior portion of the kidney 

 (genital portion) is connected with the generative organs. Trans- 

 verse canals (u c), are given off from a collecting duct, which is 



Fig. 318. Urogenital system of tho 

 Amphibia (Triton). Diagrammatic. 

 A Female. B Male, r Kidneys ; on the 

 surface of which the nephrostomata are 

 indicated. sug Ureter. od Oviduct. 

 m Mullerian duct. ve Efferent duct of 

 the testes, t Testes, ov Ovary, u Uro- 

 genital orifice (partly after Spengel). 



placed between these two organs. 



