448 UNIONIDiE, THEIR SOFT PARTS 



Margaritana det.toidea, Lea. Trans. Amer. Phil. Son., (2,) vol. vi. pi. 13, fig. 38. Obs. vol. ii. p. 43. 



Branchial uterus occupies the whole width of the outer branchiaa. Branchial rather 

 large, inner ones slightly the larger, nearly straight below, free nearly half the length 

 of the abdominal sack. Palpi small, subtriangular, not united on the posterior edges. 

 Mantle whitish, thin, thickened on the margin, with numerous quadrate maculations 

 on the outer edges. Branchial opening rather large, with numerous small papillae. 

 Anal opening small, with very minute papillae. Super-anal opening long, colored on 

 the inner edges and slightly united below. Color of the mass whitish. 



Embryonic shell subtriangular, light-brown, has hooks. See Journ. Acad. Nat. Sci. ? 

 (2,) vol. iv. pi. 5, fig. 30, and Obs. vol. vi. p. 49. 



Columbus, Ohio, H. Moores. 



Remarks. — This small species has the usual character of Margaritana in having 

 brownish maculations on the outer posterior edges of the mantle. These macula- 

 tions are not, however, confined to the genus Margaritana, as I have found them to 

 exist in Unio triangularis and TJnio fabalis. 



Margaritana confragosa = Alasmodonta confragosa, Say. Disseminator, 1829, and Amer. Conch., 

 pi. 21. 



A single specimen only, a male, was received. 



Branchial very large, nearly semicircular, inner ones much the larger, free the 

 whole length of the abdominal sack. Palpi very large, pendant, sublimate, united half 

 way down the posterior edges. Mantle rather thin, with a thickened broad margin. 

 Branchial opening rather large, with numerous small, brown papillae. Anal opening 

 very small, with very minute papillas. Super-anal opening large and united below, 

 with a dark line on the inner edges. Color of the mass whitish. 



New Harmony, Indiana, James Sampson. 



Remarks. — I have not had the advantage of examining the female of this remark- 

 able and very beautiful species. There being a single male only received. It would 

 be very important to know the character of the embryonic shell. The absence of 

 maculations on the exterior edges of the mantle, so usually existing in this genus, is 

 an observable character in this species. 



Margaritana complanata, = Alasmodonta complanata, Barnes. Amer. Journ. Sei.,vol. vi. p. 278. 



Branchial uterus occupies the whole length of the outer branchiae, enormously ex- 

 tended — width 3| inches, length li, thickness I, probably containing some millions 

 of embryonic shells ready to be extruded. Branchiae large in the male, rounded 

 below — in the female with distended young, the outer branchiae are so much en- 

 larged as nearly to conceal the inner ones, being rounded posteriorly, gently curving 

 to the anterior end, free nearly the whole length of the abdominal sack. Palpi large. 



