No. 6.] BLADDERS OF THE TESTUDLXATA. 293 



partly unites with that of the other side, partly diverges to the 

 tendinous ligament which is seen in the middle line of the 

 cloaca. The peritoneal covering continues over on to the anal 

 bladders and unites, by means of a fold, with the part of the 

 peritoneum which overspreads the posterior surface of the 

 bladder. By means of the two membranous expansions before 

 and behind, each bladder becomes surrounded as with a loop 

 which must draw itself together as soon as the above-mentioned 

 muscle contracts. According to Budge (5) it is very improbable 

 that these " anal bladders " are true bladders and serve for the 

 reception of urine. The true bladder has the shape and struc- 

 ture of the homologous organ in other vertebrates, but the 

 "anal bladders," as Budge {5) shows, seem not to possess any- 

 thing like a muscle sheath. As we have seen, Stannius (16), 

 in opposition to Duvernoy, states that the " Bursae anales " 

 are not only found in the Emydidac, but also in the land tor- 

 toises. In the Eviydidae Hoffman (9) found them in the male 

 as well as in the female of Cleimnys and Emys. He examined 

 these bladders and distinguished in them three layers — a peri- 

 toneal layer, a muscle-fiber layer, and a mucous membrane. 

 The muscle-fiber layer is very strongly developed and permits 

 great expansion and vigorous contraction. He says : " What 

 the function of these bladders may be has remained entirely 

 unknown to me." According to him they are wanting in the 

 sea turtles, C/ic/onia imbricata Schweigg. {Chelonc imbricata 

 Boulenger) and CJiclonia viridis Temm and Schleg {Chelonc niy- 

 das Boulenger). In the CJiclydidae he found them in Che I any s 

 victoria Gray {Eviydnra krcjftii Boulenger), Chclodina longicol- 

 lis, and CJielys fimbriata. In the last-named species they are 

 very large and very thin-walled. 



Of the TjionycJiidac he examined a male of Trionyx acgyptia- 

 cns Geoff r. and a female of Trionyx sinensis. The "accessory 

 bladders " were present in the male of Trionyx aegyptiaais 

 Geoff r. {Trionyx triungtds Boulenger), and were distinguished 

 by their unusually thin walls, as in Chclys fimbriata. They 

 were not present in the female of Trionyx sinc?isis Wiegm. 

 He says the occurrence of these " anal bladders " in the Triony- 

 chidae shows that the view of Duvernoy is incorrect. 



