454 UNIONIDJE, THEIR SOFT PARTS 



tirelv, acutely angular at the posterior end, not united on the edges even above the 

 junction with the mantle. Mantle white, large, rather thick, thicker on the inferior 

 margin, greatly extended on the posterior dorsal margin. Branchial opening rather 

 large, with numerous rather small papillae, brownish inside and out. Anal opening 

 very small, brownish inside and out, crenulate on the edges. Super-anal opening 

 very long and very far removed from the anal opening, slightly colored on the edges. 

 Color of the mass white. Form of the whole mass subtriangular. 



Embryonic sliell subtriangular, has hooks, very nearly the same with A. Lewisii. 

 See Joum. Acad. Nat. Sci., (2) vol. iv. pi. 5, fig. 32, and Obs. vol. vi. p. 49. 



Scott River, California, Dr. Trask. 



Remarks. — This is a winged species of Anodonta, and the mantle is extended into 

 the interspace, forming an elevated angle. The palpi are very remarkable for their 

 form and size, and their envelopment of the mantle. Their width is about four 

 times their length. 



Anodonta gigantea, Lea. Trans. Amer. Phil. Soc. (2), vol. vi. pi. 1, fig. 1, and Obs. vol. ii. p. 1. 



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



Branchial very large, thick, gently curved below, posteriorly very oblique, inner ones 

 somewhat the larger, free two-thirds the length of the abdominal sack. Palpi very 

 large, obliquely long and angular, united two-thirds down the posterior edges. Mantle 

 rather thick, with a broad and very much thickened margin. Branchial opening 

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

 without any papillae or crenulations. Super-anal opening slightly colored, united 

 below for some distance. Color of the mass whitish. 



Columbus, Mississippi, Dr. Spillman. 



Anodonta Oregonensis, Lea. Trans. Amer. Phil. Soe., (2,) vol. vi. pi. 21, fig. 67, and Obs. vol. ii. p. 80. 



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

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

 Palpi large, suboval, united at the upper part of the posterior edges. Mantle thin, 

 thicker towards the margin. Branchial opening large, with numerous small, brownish 

 papillae. Anal opening very small, with brownish crenulated edges. Super-anal 

 opening large, united for some distance below. Color of the mass dirty white. 



Embryonic shell triangular, light-brown, has hooks, almost exactly the same with 

 A. Lewisii. See Journ. Acad. Nat. Sci., (2,) vol. iv. pi. 5, fig. 32. Obs. vol. vi. p. 49. 



Oregon, Dr. C. B. R. Kennerly of the Northwestern Boundary Survey. From the 

 Smithsonian Institution. 



Remarks. — I am indebted to Prof. Henry, Secretary of the Smithsonian Institution, 

 for the advantage of examining the soft parts of this species. The difficulty of get- 



