Ortmann: Families \\n Genera oi \.\r. 359 



again at aboul the middle of the lower margin. The inner edge has 

 crowded, verj fine papilla?, which decrease anteriorly, and the anterior 

 part of the edge is smooth. The since between the two edges is 

 of a peculiar spongy structure, full of what appear as finely rounded 

 i ir elongated pores. 



In the male the two edges of the mantle are subparallel and close 

 together, as usual, and the inner one has very minute papillae. 



The color of the soft parts is generally whitish or yellowish white. 

 Outer edge of mantle grayish posteriorly, in the region of the anal and 

 supra-anal blackish, not spotted. Papilla? of branchial brown, but 

 this color does not run forward along the inner edge, and the inner 

 edge itself and the spongy space between the two edges is snow-white. 



Truncilla florentina (Lea). 



One gravid female has been received from B. Walker. It is from 

 Shoals Creek, Lauderdale Co., Alabama, collected Nov. 2, 1909, by 

 H. H. Smith. 



Soft parts practically identical with those of T. rangiana, but the 

 color of the margin of the mantle is different. Here both edges of the 

 mantle are black-brown all around, and the space between the two edges 

 is deep black. There is also in this region a deep black streak on the 

 inside of the inner edge. The outer edge is slightly scalloped, cor- 

 responding to the dentate margin of the shell. In the specimen at 

 hand, the spongy space is covered with numerous low granules, which 

 I do not see in T. rangiana. 



Glochidia like those of the other species; length 0.23; height o.2> 

 mm. (see Plate XX, fig. 12). 



In this species also the post-basal expansion is somewhat different 

 in texture from the rest of the shell, contrary to Walker's statement. 

 It resembles very closely the structure seen in T. capsceformis. 



Truncilla capsaeformis (Lea). 



One male and one sterile female, received from B. Walker, from tin- 

 South Fork of Cumberland River, Burnside, Pulaski Co., Kentucky, 

 are at hand. 



Soft parts essentially those of T. rangiana and florentina, and in 

 color agreeing with those of T. florentina, although the streak of 

 pigment on the inside of the inner edge of the mantle is absent. There 

 are also low granules upon the spongy space, but they are finer 



