444 UNIONIDiE, THEIR SOFT PARTS 



the length of the abdominal sack. Palpi very small, suboval, united at the upper 

 posterior part. Mantle very thin, with a delicate-colored margin. Branchial open- 

 ing rather large, with numerous small, brownish papilla?. Anal opening large, with 

 numerous small, brownish papillae. Super-anal opening colored within the edges and 

 slightly united below. Color of the mass whitish. 



Embryonic shell pouch-shape, white, has no hooks. 



Uniontown, Alabama, E. R. Showalter, M. D. 



Remarks. — This is one of the group of three species which have that very remark- 

 able characteristic of folded branchial uterus, which I have described and figured, as 

 referred to above. The specimens examined had from ten to fifteen folds in each of 

 the outer branchiae, like phaseolus and Woodwardianus, but there are differences in 

 each of them. The embryonic shell is allied to both, but it is more elongate than 

 phaseolus and less so than Woodwardianus. In the general character of the soft parts 

 it is like Woodwardianus. 



TJnio compactus, Lea. Jour. Acad. Nat. Sci., (2,) vol. iv. pi. 28, fig. 98, and Obs. vol. vii. p. 36. 



Branchial uterus occupies the posterior portion of the outer branchiae in about a 

 dozen ovisacks. Branchial large, nearly semicircular, inner ones much the larger, 

 free about half the length of the abdominal sack. Palpi very small, nearly oval, 

 united only at the upper part of the posterior edges. Mantle thin, thickened at the 

 margin, below the branchial opening on each side is placed a singular enlargement, 

 which is black inside and has crenulated edges, the posterior basal margin having 

 papillae. Branchial opening large, with small reddish brown papillae. Anal opening 

 small, with minute light brown papillae. Super-anal opening rather large, with 

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



Embryonic shell light brown, subrotund, has no hooks, near to perplexus. See Jour. 

 Acad. Nat. Sci. (2) vol. iv. pi. v, fig. 21. Obs. vol. vi. p. 48. 



Coosa River, Alabama, E. R. Showalter, M. D. 



Remarks. — This small species is near to penitus, Con., in its outline and 

 epidermal markings. The outline of the embryonic shell is nearly the same as that 

 of perplexus, but it differs in the compactus being more rotund, the dorsal line being 

 shorter. The enlargement below the branchial opening is different from any I have 

 seen, being rather small, the segment of about the third of a circle, black inside and 

 regularly crenulate on the edge. This process, while placed nearly in the same 

 position, is entirely different in its form from the caruncle in parvus, Bar., figured in 

 the Jour. Acad. Nat. Sci. (2), vol. iv. pi. 29, fig. 102. Obs. vol. vii. p. 39. 



TJnio Tuomeyi, Lea. Trans. Amer. Phil. Soc. (2), vol. x. pi. 13, fig. 4. Obs. vol. v. p. 12. 



Branchial uterus occupies the whole length of the outer branchiae. Ova were 



