94 thp: xautilus. 



covered with a thick tar-colored or very dark green epidermis; 

 interior lined with a dark peach blossom nacre, sometimes salmon 

 colored. There is a single, erect, pyramidal, coarsely striated car- 

 dinal tooth in the right valve, and two triangular, pyramidal teeth 

 in the left valve ; lateral teeth long, compressed and slightly curved. 

 Length, 82 inches; height, 2 inches; breadth, 1 inch. 



This is our most common fresh-water clam. It is found in all the 

 rivers in the U. S. which empty into the Atlantic Ocean, but is not 

 found west of the Atlantic slope. It is also abundant in almost all 

 the ponds east of the Allegheny mountain.s. It might be collected 

 by bushels in the Blackstone River, CunlifF's Pond, Old Warwick 

 Pond and many others. It is a favorite article of food for the musk- 

 rat, which devours them in great numbers, leaving piles of empty 

 shells on the edges of the streams and ponds. It is a very curious 

 thing how the muskrat can open the shell and devour the animal 

 without leaving a mark of teeth or claw upon the shell. Specimens 

 freshly cleaned of their contents are in as fine condition for the cab- 

 inet as those obtained alive and prepared on purpose, the two valves 

 held together perfectly by the ligaments, and the edges or margins 

 of the shell unbroken. 



188. — Unio nasutus, Say. 



Syns. : 



Mya nasuta, Wood. 



Eurynea nasuta, Stimp, Perkins, Morse, etc. 



Unio rostratus, Valenc. 



Unio nasutus, Say, Con, Lea, GId. Dall, etc. 



Shell slender, very inequilateral ; beaks small, pointed and 

 slightly elevated, posfferior produced so as to form a snout, from 

 which peculiarity its specific name. There are usually two or three 

 radiating lines running from the beaks to the end of the snout. 

 Surface smooth ; ei)iderrais glossy, of a dark olive-green color, 

 becoming dusky in old specimens. !N^acre silvery Avhite, iridescent, 

 sometimes with shades of bluish or salmon ; cardinal teeth delicate, 

 compressed and directed obliquely forwards ; cavity of the beaks 

 small. Length, 3 inches ; height, U inches; breadth, | inch. 



Described by Thos. Say in Nich. Eucy. 181d. It is quite a com- 

 mon shell in the Middle and some of the Western States, but is very 

 rare in New Eng. It has been found in onlv four localities in ]Mass. 



