LACERTA in 



with the lack of respiratory function on the part of the skin, 

 the cutaneous vein is not found. The posterior cardinal 

 veins are likewise much reduced ; that on the left disappears 

 altogether, that on the right is now known as the azygos vein. 

 Lastly, the renal portal system is less well developed, and this 

 is associated with the fact that the functional kidney in the 

 adult is a new structure, the metanephros. 



Urino-Genital System. — The kidneys are paired structures 

 lying in the roof of the posterior part of the coelomic cavity, 

 which connect with the base of the allantoic bladder (where 

 the latter opens into the cloaca) by means of ducts called 

 ureters. These kidneys are not the same as the mesonephric 

 kidneys of the animals previously described ; they are meta- 

 nephric kidneys, and serve excretory functions only, never 

 connecting with the genital organs. Otherwise, they are 

 similar in structure to the mesonephros, and consist of Mal- 

 pighian corpuscles with glomeruli and tubules. The meta- 

 nephros develops later than the mesonephros, and out of the way 

 of the posterior cardinal veins. The mesonephros is present 

 in early stages of development, but does not function as an 

 excretory organ in the adult. As the renal portal system is 

 associated with the mesonephros, the disappearance of the one 

 is correlated with the reduction of the other. 



In the female, the mesonephros disappears in the adult, 

 together with the Wolffian duct. The Miillerian duct persists 

 as the oviduct and serves to convey the eggs (which drop from 

 the ovary into the ccelom) to the exterior via the cloaca. Glands 

 in the oviduct secrete a shell round the egg, for it is laid on 

 dry land, and not in water. The embryo develops within a 

 membrane, the amnion, for which reason reptiles, birds, 

 and mammals are called Amniota. In the male, the Miillerian 

 duct is absent, but the mesonephros and Wolffian duct persist, 

 serving only to evacuate the sperms. The testis is connected 

 with the mesonephros by vasa efferentia in the ordinary manner, 

 and the tubules of the mesonephros, through which the sperms 

 pass, form the epididymis. The epididymis is really very 

 long, and when unravelled it forms a tube which in man is 

 over twenty feet long. During their passage through it, the 



