AND EMBRYONIC FORMS. 455 



ting preserved specimens from such distant habitats is extreme, and Dr. Kennerly and 

 other gentlemen attached to these national expeditions, render great service to science 

 in having made collections of the natural history in the regions they passed through. 



Anodonta fragilis, Lam. An. sans Vert., vol. vi. p. 85. 



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



Branchial large, inner ones larger anteriorly, free nearly the whole length of the 

 abdominal sack. Palpi rather large, subtriangular, united nearly the whole length 

 on the posterior edges. Mantle very thin. BrancJiial opening large, with numerous 

 small, brown papillae. Anal opening rather large, with crenulate edges. Super-anal 

 opening rather large, colored on the inner edges, united for some distance below. 

 Color of the mass dirty white. 



Punch Bowl, near Grand Rapids, Michigan, J. A. McNeil, per Dr. Lewis, of 

 Mohawk, New York. 



Remarks.— This remarkably delicate and fragile species is so nearly like to a speci- 

 men which I obtained from Baron Ferussac, in Paris, as the fragilis, Lam., from 

 Newfoundland, many years since, that I cannot consider it more than a variety. 

 Mr. Anthony has distributed it under the name pallida. I received quite a number 

 of specimens in alcohol, every one of which were females, having ova in the ova- 

 rium, but none had ova in the branchial uterus. The outer hard parts of this 

 species is remarkably thin and diaphanous. With a moderately good microscope, 

 the angular compartments of the base membrane may easily be distinguished. The 

 epidermis is so delicate and smooth that the minute granules or knobs which have 

 been described and figured in my paper as to exist on the embryonic shells, (Journ. 

 Acad. Nat. Sci., (2,) vol. iv. and Obs. vol. vi.), may be easily seen to exist on the 

 epidermis of the mature shell, within the area of the base membrane compartments. 

 I have observed the same character to exist on delicate specimens of Anodonta fiuvi- 

 atilis and Unio ochraceous. These compartments may be of four, five, or six sides ; 

 but usually of six. 



Supplement to "Descriptions of Soft Parts and Embryonic Forms of one hundred and 

 forty-three species of Unionidce of the United Stales." By Isaac Lea. 



Unio ochraceus, Say. Nicholson's Ency., Am., Ed. Art. Am. Conch, and Trans. Anicr. Phil. Soc, (2) 

 vol. vi. and Obs. vol. ii. p. 49. 



Branchial uterus . Branchial large, inner ones much the larger, very thin, 



nearly semicircular, united the whole length of the abdominal sack. Palpi small, 

 ovate, united on the upper part of the posterior edges. Mantle very thin, while. 



