314 COMPARATIVE ANATOMY. 



Wolf fian duct takes place (Fig. 244. MG}. The latter probably serves in 

 the male as a urinogenital duct, and in the female as a urinary duct only. 

 Should more complete histological examination confirm these statements, the 

 mode of development of the generative organs of cartilaginous Ganoids will be 

 seen to resemble closely those of Elasmobranchs and Amphibian?. 



Hermaphrodite structures have been observed in certain Fishes : in 

 the different species of S err an us, for instance, they are constantly present. 

 Hennaphroditism also occasionally occurs in Sargus, Gadus morrhua, and 

 many others. 



In the Dipnoi, the gonads and their ducts lie along the outer 

 border of the kidneys. During the breeding-season they become 

 greatly enlarged, and extend round the entire gut. The oviducts 

 are long and slightly coiled, reminding us in many points of those 

 of Amphibia : each communicates with the body-cavity by a funnel- 

 shaped aperture near the pericardium, and is provided with a well- 

 developed albumen gland. The ovaries undergo the greatest 

 variations according to age and the time of year. In the unripe 

 condition they have the form of long and narrow bands, which 

 extend along the whole body-cavity. In the young Ceratodus 

 they are distinctly lobulated, and in both Ceratodus and Proto- 

 pterus each ovary of the adult has the form of a thin-walled sac, 

 in the inner walls of which the ova are developed. The eggs are 

 shed into the body-cavity by the bursting of the walls of the sac, 

 and they pass thence into the oviducts. 



In the male, the manner in which the sperm is conducted to 

 the exterior is not certainly known : it may possibly pass out 

 through the abdominal pores. The Mullerian ducts, although 

 less developed than in the female, are clearly present in the male. 

 The structure of the testis requires further investigation. 



Amphibia. The gonads of Amphibia are usually situated in 

 about the middle of the body-cavity : they are paired and symme- 

 trical, and lie right and left of the vertebral column ; their form is 

 usually modified by the shape of the body. Thus in the Gymno- 

 phiona (Fig. 239, Ov), the ovary has the form of a long and 

 narrow band, while the testis is made up of a long chain of small 

 bodies united together by a collecting duct (Fig. 246, Ho, Sg}. 

 Each individual portion of the testis of Caecilians is made up of a 

 double row of rounded capsules (Fig. 246, K], in which the sperm 

 is formed, and from which it is passed into a collecting duct (Sg), 

 which perforates each portion of the organ. A transverse canal 

 (Q) is given off from the free portion of the collecting duct lying 

 between every pair of testis lobes; this passes towards the kidneys 

 (N,N], and opens into a longitudinal canal (Z). From the latter 

 the sperm passes through a second system of transverse canals 

 (Q l , Q 1 } to the Malpighian capsules, and thence through the urinary 

 tubules into the urinogenital duct (HS). 



The male generative apparatus of all Urodela and certain 

 Anura (Bufonidoe), corresponds in the main with the arrange- 



