No. 6.] BLADDERS OF THE TESTUDINATA. 295 



smaller than those of T. Carolina. In both species the size 

 and appearance of these bladders indicate that they have 

 become functionless. 



In general it may be said that the "accessory bladders" are 

 large oval or cylindrical sacs, opening dorsally on each side of 

 the cloaca, near its anterior end. They lie in the pelvic region 

 and extend into the peritoneal cavity, covered by the perito- 

 neum. In some species the lungs are in contact with a large 

 portion of their upper surfaces. By means of a fold which 

 comes between their openings, a 



part of the cloaca in front of Ac. bl.—[^\^^\^i£f^i '\..Ac./,i. 

 them can be closed off, so that 

 the bladders may communicate 

 directly with the cloaca, thus 

 completely excluding all the other ^ „ , , , . , u , 



'■ •' ° t iG. I. — External dorsal view of the cloaca 



openings except the anus. In of r(?rra/^«^ f«r£>//«j, showing the size 



P , _ , . of the accessory bladders. 



many of the iresh specmiens 



these bladders were found to contain a clear liquid. When 

 empty their external surface is corrugated like that of the 

 true bladder, and their internal mucous membrane is thrown 

 into folds. 



In regard to the minute structure of the " accessory bladders " 

 the following data may be given: The "accessory bladders" 

 have a muscular wall lined with a mucous membrane and cov- 

 ered with a serous coat. The muscular coat is made up of 

 three layers, the inmost being incomplete. The principal fibers 

 are longitudinal and circular, and the latter are arranged in 

 bundles. Sections of the bladder and " accessory bladders " 

 of Chrysentis picta, Chelydra serpentina, and Emys blandiiigii 

 were made and compared. The mucous membrane is lined 

 with epithelial cells which are arranged in layers. The cylin- 

 drical cells in the upper layer are very long and narrow. They 

 gradually become more slender below, and again show expan- 

 sions where the nuclei lie. The protoplasm of these cells is 

 very finely granular. Three to four rows of round cells lie 

 between the narrow projections of the cylindrical cells. The 

 mucous membrane of the bladder is. lined with epithelial cells 

 which have a structure and arrangement similar to that of the 



