AXD PEBITONEAL CANALS IN CHELONIA. 435 



and of some Struthious birds. The penial and clitorid portion of 

 the cloaca in Trionychidse and Emydidse is richly coloured with a 

 purplish-black pigment, which invests the whole of the glans and 

 the hood or prseputium and a considerable portion of the pillars 

 of the penis and clitoris anterior to the glans. A similarly co- 

 loured pigment also occurs in the openings of the oviducts of 

 some of the Trionychidae, But in the Southern-Asiatic species 

 of land-tortoise referable to the subgenus Peltastes the cloaca 

 and the glans are devoid of black pigment, and are generally 

 pale yellow. The glans penis appears to have a form peculiar to 

 each leading group, and is doubtless in its construction specially 

 adapted to ensure the most perfect efficiency of function in spe- 

 cial relation to the habits of life of the animal. There is a ter- 

 restrial and there is an aquatic glans penis, the latter having essen- 

 tially the character of a grasping organ. 



It is not the object of this paper to describe the copulative 

 organ, so far as the glans is concerned ; but I may be permitted 

 to remark that perhaps in no class of animals is the glans clitoridis 

 so perfect a reproduction of the glans penis as in this most 

 interesting group of vertebrates. So alike are they in young Che- 

 lonians, that a direct appeal to the peritoneal cavity is necessary 

 to determine the sex. 



Before I take up the question of the peritoneal canals and their 

 relation to the other parts of the penis, the title of this paper neces- 

 sitates that the cloacal bladders should be first described. 



The anal pouches, or cloacal bladders, as they might be more 

 properly called, were first accurately described by Bojanus*, in 

 his account of the anatomy of the common Emyde of Southern 

 Europe, Emys europcea ; but since his day they do not appear 

 to have received that attention which their importance apparently 

 demands, and which is indicated by the circumstance that they 

 occur in some of the well-marked types and are absent in others. 

 They are the structural equivalents of the similar bladders or 

 vessels which are met with in the crocodiles, and in most lizards 

 and snakes, in various degrees of development ; but they attain 

 the highest differentiation in this group. 



I have recently had the opportunity to examine a number of 



Asiatic species belonging to difterent genera ; and I find that these 



bladders occur in JEmys trijuga, E. crassicollis, Batagur dhongoka, 



B. lineatus, B. fmcus, B. {Morenia) ocellata, B. (Hover, ia) beru- 



* Anat. Testucl. eiu-op. 1«19-21. 



