UROGENITAL ORGANS 



363 



ductules to the posterior end of the mesonephros, the epididymis thus being 

 posterior in position. Less is known of the structures in Ceratodus, but the duc- 

 tules are more numerous and the epididymis is anterior. 



AMPHIBIA. — The pronephros (developing from two somites in urodeies, 

 three in anura and from ten to thirteen in cacilians) retains its functions in 

 urodeies and anura until the metamorphosis, when its tubules degenerate. The 



Fig. 384. Fig. 385. 



Fig, 384. — Diagram of (^4) male and {B) female organs of urodele, after Spcngcl. 

 e, vasa efferentia; /, longitudinal duct; m, MUUerian duct; ms, mesonephros with nephro- 

 stomes indicated; 0, ovary; ot, ostium tubae; I, testis; w, Wolffian duct. 



Fig. 385. — Male urogenital organs of Epicrium, after Spengel. o, anus; ft.'urinary 

 bladder; cl, cloaca; /, fat bodies; m, MUllerian ducts; tng, glandular part of same; r, 

 rectum; /, testes; //, longitudinal testicular canal; w, Wolffian body. 



part of the coelom into which the pronephric nephrostomes open, tends to be cut 

 off as a separate chamber, while the blood supply may form a glomus. The early 

 mesonephros consists of a tubule with its nephrostome, tubule and glomerulus 

 to each somite, but in the adult this metamerism is lost (except anteriorly) by the 

 development of secondary tubules, each like the original, the nephrostomes 

 sometimes numbering over a thousand on the ventral surface of each Wolffian 

 body. These nephrostomes persist with their normal connexions in corcilians 



