42f, UNIONID^E, THEIR SOFT PARTS 



anal opening enormously large, colored on the edges and united below. Color of the 

 mass whitish. The adducted muscles very large. 



Cincinnati, Ohio, J. Clark ; and Columbus, Ohio, H. Moores. 



Unio rangjanus, Lea. Trans. Amer. Phil. Soc, (2,) vol. vi. pi. 18, fig. 26, and Obs. vol. ii. p. 95. 



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



Branchiae rather large, nearly semicircular, inner ones much the larger, united the 

 whole length of abdominal sack. Palpi rather small, suboval, not united on the pos- 

 terior edges. Mantle thin, very much thickened and prolonged on the inferior poste- 

 rior portion, which is here enlarged into a flap on each side, having an offset, the 

 edge of which is slightly crenulate. Branchial opening rather small, with minute 

 papillae. Super-anal opening rather large, colored on the inner edges. Color of the 

 mass whitish. 



Columbus, Ohio, H. Moores. 



Remarks. — This species is very nearly allied to perplexus in the outward hard parts, 

 and the soft parts seem to differ but little. Two of the female specimens examined 

 were not found to have the edges below the super-anal opening united, but this may 

 have been accidental, as they were not in good order. 



Unio multiradiatus, Lea. Trans. Amer. Phil. Soc. (2) vol. iii. pi. 9, fig. 15, and Obs. vol. i. p. 48. 



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

 There were thirteen ovisacks on one side, but not so many on the other. Branchiae 

 large, nearly semicircular, inner ones much the larger, united the whole length of 

 the abdominal sack. Palpi small, subtriangular, united a very short distance down 

 the posterior edges. Mantle thin, thicker along the margin, with a few papilla} 

 below the branchial opening, which are larger in the female than in the male. In 

 the female there is at the lower termination of these papillae a flat enlargment or flap- 

 like process, as in ventricosus and other allied species. Branchial opening rather 

 large, with numerous rather large papillae. Anal opening small, crenulate on the 

 edges. Super-anal opening rather large and united for some distance below. Color 

 of the mass whitish. 



Embryonic shell ovato pouch-shape, clear white, has no hooks. See Journ. Acad. 

 Nat. Sci., (2) vol. iv. pi. 5, fig. 17, and Obs. vol. vi. p. 47. 

 Columbus, Ohio, H. Moores. 



Remarks. — This is one of the species of Unio in which the papillae are absent on 

 the anal opening. 



Unio rectus, Lam. An. sans Vert., vol. vi. p. 74. 

 Branchial uterus occupies the posterior half of the outer branchiae, there being 



