EXCRETORY AND REPRODUCTIVE SYSTEMS. 547 



are shut, and the floor of the mouth at the same time raised, 

 air is forced through the glottis into the lungs. 



Excretory System. 



The paired kidneys are elongated organs situated dorsally 

 and posteriorly in the region of the urostyle. The waste 

 products which they filter out of the blood pass backward 

 by two ureters which open separately on the dorsal wall of 

 the cloaca, without any communication with the bladder. 

 The ureter or Wolffiah duct is seen as a white line along the 

 outer side of each kidney ; in the male it functions also as 

 the duct of a testis. On the surface of each kidney is a 

 longitudinal yellowish streak, which is an adrenal gland of 

 unknown significance, and little spots mark ciliated apertures 

 or nephrostomes, which remain as communications between 

 the abdominal cavity and the renal veins, though they are 

 apparently in embryonic life connected with the urinary 

 tubules. 



Reproductive System. 



The males are readily distinguished from the females by 

 the swollen cushions on the first fingers, and there are some 

 other slight external differences. The breeding season begins 

 in spring, and then the males trumpet to their mates. The 

 male clasps the female with his fore limbs, and retains his 

 hold for several days, fertilising the ova as they pass out into 

 the water. 



The paired testes are oval yellowish bodies lying in front 

 of the kidneys; the spermatozoa pass by vasa efferentia 

 through the anterior part of the kidney into the Wolffian 

 duct, which functions both as a ureter and as a vas deferens. 

 In the male of R. esculenta. the vas deferens is dilated for 

 some distance after leaving the kidney ; in R. temporaries 

 it bears on the outer side near the cloaca a dilated glandular 

 mass or " seminal vesicle." In the males rudiments of the 

 Miillerian ducts are sometimes seen. 



The paired ovaries when mature are large plaited organs, 

 bearing numerous follicles or sacs containing the pigmented 

 ova. The ripe ova are liberated into the body cavity, and 

 moved anteriorly towards the heart near which the oviducts 

 open. These oviducts are long convoluted tubes, anteriorly 



