GENITAL ORGANS 469 



opening into the cloaca, and each communicates anteriorly with 

 the body-cavity by a funnel-shaped aperture. The wall of the 

 oviduct secretes albumen round the eggs as they pass along it. 



In Protopterus and Lepidosiren, the greater portion of the testis 

 is composed of numerous sperm-producing ampullae opening into 

 a longitudinal duct continuous with a cavity in a simplified 

 posterior prolongation of the gonad, in which no sperms are 

 formed, and which converges posteriorly, fusing with its fellow in 

 Protopterus : it serves merely as a duct and as a vesicula seminalis. 

 From the posterior end of this portion a testicular network arises 

 in Lepidosiren, from which about six vasa efferentia pass into the 

 Malpighian capsules of the mesonephros (" posterior epididymis," 

 p. 455), while in Protopterus there is only a single large and 

 irregular vas efferens on either side. Thus the posterior end of 

 the mesonephric duct is urinogenital in function. 



In Ceratodus the manner in which the sperms are conducted 

 from the testis to the exterior is not definitely known. The 

 Miillerian ducts in this geriUs are retained in the adult, and 

 possess a lumen throughout : in Protopterus they undergo further 

 reduction, and apparently the middle part disappears, the posterior 

 end fusing with its fellow and ending blindly at the base of the 

 urinogenital papilla, while in Lepidosiren only the anterior end 

 persists. 



Thus a communication between the testis and kidney occurs 

 in Elasmobranchii, certain Ganoidei (Lepidosteus, Amia, 

 Acipenser), Dipnoi, Amphibia, and Amniota, and on the assump- 

 tion that the condition in Polypterus and Teleostei is a secondary 

 and not a primary one, an attempt to bring these latter into line 

 with the majority of Vertebrates in this respect is represented 

 diagrammatically in Fig. 3o3. 



Amphibians. The form of the gonads of Amphibia is 

 usually modified in correspondence with the shape of the body. 

 Thus in the Gymnophiona the ovary has the form of a long and 

 narrow band, and the testis consists of a long chain of small bodies 

 united together by a collecting duct (Fig. 354). Each individual 

 portion of the testis of Cascilians is made up of a double row of 

 rounded capsules in which the sperms are formed, and from which 

 they are passed into a collecting duct, which perforates each portion 

 of the organ. A transverse canal is given off from the free portion 

 of the collecting duct lying between every pair of testis-lobes ; 

 this passes towards the kidneys, and opens into a longitudinal 

 canal. From the latter the sperms pass through a second system 

 of transverse canals to the Malpighian capsules, and thence through 

 the urinary tubules into the urinogenital duct. 



The male generative apparatus of all Urodela and certain 

 Anura (Bufonidae) corresponds in the main with that "seen in 

 Caecilians, except as regards the form of the gonads : thus the testis 



