420 UNIONIDiE, THEIR SOFT PARTS 



sufficient importance to make generic divisions as proposed by Prof. Agassiz. The 

 papillae on the margin of the mantle below the branchial opening were larger, more 

 distant than on the branchial opening, and were colored. On the posterior inner 

 margin of the mantle, inside of the papillae, the females have an enlargement for 

 some distance, which was covered with whitish clouded spots. 



Unio herplexus, Lea. Trans. Amer. Phil. Soc, (2,) vol. iv. pi. 17, fig. 42, and Obs. vol. i. p. 122. 



Branchial uterus occupies the posterior half of the outer branchiae. Branchial 

 small, light liver-brown, rather thick, rounded below, inner ones the larger, united the 

 whole length of abdominal sack. Palpi rather small, transverse, subrotund, united 

 half way down the posterior edges. Mantle rather thick, dark on the margin, very 

 much enlarged, thickened, and extended into a flap offset on the posterior inferior 

 margin, blackish on the border, the inner double edges having numerous small pa- 

 pilla?. Branchial opening rather large, brown, with numerous small, brown papillae. 

 Anal opening small, with very minute brown papillae. Super-anal opening mode- 

 rately large, brownish and somewhat maculate within, edges thick and united below. 

 Color of the mass whitish, inclined to salmon. 



Embryonic shell subrotund, clear white, has no hooks. See Jour. Acad. Nat. Sci. 

 (2,) vol. iv. pi. 5, fig. 21, and Obs. vol. vi. p. 48. 



Columbus, Ohio, H. Moores. White River, Indiana, D. H. Shaffer. 



Remarks. — The remarkably extended form of the posterior part of the valves of the 

 female indicate the extended fleshy flap, which is always found in the female of this spe- 

 cies. A number of fine specimens were sent tome from the two habitats mentioned above. 

 The fleshy margin and the flap extending beyond are white outside, but inside the 

 margin is black while the flap extending beyond is brownish, maculate with black. 

 In one of the female specimens there is a small process, like a style, coming appa- 

 rently from the liver over the anterior adductor muscle. It is white and thread-like, 

 about half an inch long and enlarged at the point. It suggested the idea of an ovi- 

 positor if such a thing ever existed in the Vnionidos. The style found in the female 

 of cariosus is much larger and longer than this and is transparent. 



Unio triangularis, Bar. Am. Jour. Sci., vol. vi. p. 272. 



Branchial uterus occupies the posterior part of the outer branchiae ; it is large, white 

 and crenulate at the lower edges. Branchial not large, inner ones the larger anteri- 

 orly, united the whole length of abdominal sack. Palpi very small, subelliptical, 

 united a short distance on the posterior edges. Mantle thin, thickened on the margin, 

 maculate on the outer posterior edges; below the branchial opening there is a fleshy, 

 brownish black enlargement and numerous rather large papillae. Branchial opening 

 rather small, with very small papillae. Anal opening without papilla?, but corrugated 

 on the edges. Super-anal opening small, united below. Color of the mass very white. 



