AND EMBRYONIC FORMS. 415 



Remarks. — About sixty specimens were received from the above two habitats, 

 none of which had the embryonic shell formed. Those from Major Downie were 

 collected in March, and the females had passed some of their ova into the branchial 

 uterus, which were there becoming matured. 



Unio tenerus, Ravenel. Catalogue. 



Branchial uterus occupies the posterior portion of the outer branchiae, like cariosns, 

 in large ovisacks, and having a dark border below. There were sixteen ovisacks in 

 each of the outer branchiae. Branchice rather small, inner ones much the larger, 

 edge of the branchia not attached to abdominal sack, but still there appears to be 

 no opening to the interior of the leaf. Palpi rather long, subtriangular, united but 

 a short distance. Mantle thickened at the lower margin, where it is .slightly lead 

 color, has papillae below the branchial opening. Branchial opening with numerous 

 small, dark papillae. Anal opening small, with numerous minute papillae. Super- 

 anal opening not very large, edges colored, united below. Color of the mass 

 whitish. 



Near Darien, Georgia, J. Hamilton Couper, Esq. and Major T. C. Downie. 



Unio Shepardianus, Lea. Trans. Ainer. Phil. Soc. (2), vol. v. pi. 13, fig. 38. Obs. vol. i. p. 207. 



Branchial uterus -. No ova were found here, but they were numerous in the 



ovarium. Branchial very wide and narrow, nearly straight below, the inner ones 

 somewhat the larger, free nearly the whole length of the abdominal sack. Palpi 

 long, transverse, short at the posterior end, where the edges are not united. Mantle 

 dark, whitish along the lower margin, edges not colored. Branchial opening 

 rather large, with numerous small papillae within the row of which the lining is 

 black. Anal opening rather small, with numerous small papillae, inside of which 

 there is a black line. Super-anal opening very large, bordered with a black line 

 inside and out, that on the outside continuing along the edge to the basal margin, 

 united for some distance below. Color of the mass whitish. 



Near Darien, Georgia, J. Hamilton Couper, Esq. 



Remarks. — The specimens were about four inches wide. Several had ventral 

 muscular attachments. 



Unio Hopetonensis, Lea. Trans. Amer. Phil. Soc., vol. vi. pi. 9, fig. 24. Obs. vol. ii. p. 29. 



Branchial uterus . No ova were found here, but a number had ova in the 



ovarium. Branchice large, much curved below, inner ones nearly double the size of 

 the outer, free rather more than half the length of abdominal sack. Palpi rather 

 large, subtriangular, united for a short distance on the posterior edges. Mantle dark 

 colored, thickened at the margin. Branchial opening large, with numerous small, 

 brownish papillae. Anal opening very large, with very minute papillae. Super-anal 



