404 UNIONIDiE, THEIR SOFT PARTS 



rather small, with very minute, brown papilla?. Super-anal opening long, united 

 for a short distance below. Color of the mass whitish. 



Embryonic shell short, pouch-shape, very nearly like to that of phaseolus, Hild. 

 Jour. Acad. Nat. Sci., vol. iv. pi. 5, fig. 12. Obs. vol. vi. p. 46. 



Schuylkill River, near Philadelphia, and Buffalo, New York, by Mr. A. T. 

 Jackson. 



Remarks. — Prof. Agassiz says* that in this species, which he assigns to the genus 

 Eurynia, Raf., that the gills are united the whole length of the foot. On the con- 

 trary, they are/ree at the posterior end of the foot. 



Unio obesus, Lea. Trans. Amer. Phil. Soc, vol. iv. pi. 13, fig. 26. Obs. vol. i. p. 106. 



Branchial uterus occupies the whole length of the outer branchiae. Branchiae large, 

 inner ones the larger, round below, free nearly the whole length of abdominal sack. 

 Palpi very small, subtriangular, not united on the posterior edges. Mantle very thin, 

 slightly thickened on the edge. Branchial opening rather large, with numerous small, 

 brownish papillae. Anal opening small, with very small, numerous brownish papillae. 

 Super-anal opening small, united below. Color of the mass dirty white. 



The specimens were from Columbus, Georgia, sent by Bishop Elliott. 



Unio Kxeinianus Lea. Trans. Amer. Phil. Soc, vol. x. pi. 17, fig. 18. Obs. vol. v. p. 21. 



Branchial uterus occupies both leaves of the branchiae on both sides. Ova were also 

 found in the ovarium. Branchiae large, nearly semi-circular, inner ones much the 

 larger, free half the length of abdominal sack. Palpi rather large, subtriangular, 

 united half way down the posterior edges. Mantle thin, white and slightly thickened 

 at the edges. Branchial opening small, with small, light-brown papilla. Anal open- 

 ing rather large, dark, without papillae. Super-anal opening large, slightly united 

 below. Color of the mass white. 



Columbus, Georgia, by Bishop Elliott and G. Hallenbeck. 



Unio Dariensis, Lea. Trans. Amer. Phil. Soc, vol. viii. pi. 26, fig. 61. Obs. vol. iii. pi. 84. 



Branchial uterus occupies the whole length of the outer branchiae. Branchial very 

 large, much rounded below, free rather more than half the length of the abdominal 

 sack. Palpi moderately large, subtriangular, united half way on the posterior edges. 

 Mantle thin, with a broad margin, angular at the posterior basal margin. Branchial 

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

 small, brown papillae. Super-anal opening rather large and united below. Color of 

 the mass whitish. The ova were nearly matured in the branchial uterus, but not 

 enough to make out the form perfectly. They appeared to be subtriangular. 



* See "Shells of New England, by Stimpson," MSS., quoted; and Agassiz's paper in "Archiv fur Natur- 

 geschichte," 1852. 



