October, 1841.] 103 



In size, this species is a little larger than the Northern Grey Squirrel, (Sc. 

 leucotis,) and may be compared with the black variety of that species. The 

 ears, which are elliptical in shape and narrower than io most of our species, 

 are thickly clothed with soft, fine hair on both surfaces. The tail is very 

 long, and, instead of being distichous, as in most of the species, is in the 

 prepared specimen perfectly round. The feet are clothed with hair, par- 

 tially concealing the nails. The hair is longer, more diffuse, but not softer 

 than that of Sc. leucotis. 



Colour. The head, ears, upper surface of the legs, tail, and a broad dor- 

 sal line, black. On the sides, the hair is plumbeous at the roots, then a liiae 

 of brown slightly tipt with black. On the under surface, this species is 

 dark brownish black, from the lips to nearly the extent of the jaws. On the 

 throat, inner surface of the legs, and whole under parts of the body, there 

 is a mixture of black and brown fur, giving it a dark, rusty-brown colour. 

 There are no annulations in the hairs of the tail. 



Dimensions 



Length of the head and body, 11 inch. lines. 



tail to the end of hair, 14 " " 

 Height of ear, " 8 " 



Heel to the end of nail, 2 9 " 



When old father Linnaeus comprehended the whole of his description of 

 an American Squirrel in the single word, niger, he was not aware of the 

 number of species of Black squirrels which should yet be detected in our 

 western world, and the perplexity it would give to his successors in decid- 

 ing on the species to which he referred. 



There are now no less than eight North American squirrels, which are 

 either permanently, or in some of their varieties, black. 



The present cannot, however, be identified with any of our known species. 

 It approached nearest to the black variety of the Northern Grey Squirrel, 

 but is sufficiently distinct from that to entitle it to another name. The 

 species in the Atlantic States have, moreover, never been found west of the 

 Rocky Mountains, nor, indeed, have any but the Fox squirrel (Sc. capis- 

 tratus) been observed to the west of the Mississippi river. 



Fuller descriptions, with an account of habits, accompanied by good 

 figures of the above species, will be given in a work on the North American 

 Quadrupeds, now preparing for publication. 



Mr. Haldeman submitted the following " Description of a 

 new species of fresh water Shell." 

 Cyclas (pisidium) dentata. Shell ovate, olivaceous, inflated, 



umbones elevated ; medial and lamellar teeth well developed. 



Length 0.5 ; height 0.4 inch. Hab. Oregon : Mr. Nuttall. 



Bears considerable resemblance to C. similis, from which it 

 may be distinguished by the more elevated beaks. 



N. B. Pisidium abruptum (p. 53,) is not distinct from P. 

 dubium, Say. 



