164 



NATURAL HISTORY OF VERMOiNT. 



Part I. 



FRESH WATER AND LAND SHELLS. 



FAMILY CALYPTRACIANA. 

 Genus Ancylus. 



Generic Characters. — Sh«ll ihin, oblong-ellip- 

 tic, obliquely conic ; apex acu'e, curved back- 

 wards ; aperture elliptic j margins slisrp. Ani- 

 mal covered, not concealed, by ilie shell, with two 

 compressed lentucles and the eyes on the inner 

 part of the base ; (lot elliptic, not so wide as the 

 body. 



Jlncylus para llehis. — II a i. n E m A N. 



Description. — Shell nearly transpa- 

 rent, oblong-ovate ; epidermis thin, horn 

 color ; sides straight, slightly divergent 

 forwards ; apex subacute, moderately ele- 

 vated, with two fifths of the length of the 

 shell behind, leaning to the right. Length 

 0:2o inch, width 0.15 inch, height 0.08 

 inch. 



Remarks. — This species is found in 

 streams and ponds in many parts of the 

 New England states. It was sui)posed to 

 be Say's .*?. riruliiris, not on account of 

 any resemblance between the two shells, 

 but from the mcagerness of the description. 

 From some remarks of this learned natu- 

 ralist, comparing J. rirulnris with .1. tar- 

 djis, it seems probable that the former is 

 not an elongate species. 



Jlncijlus tardus. — Say. 



Description. — Shell nearly transpa- 

 rent, elliptical ; epidermis thin, horn col- 

 or ; sides somewhat curved; apex snb- 

 acute, elevated, a little behind the mid- 

 dle, leaning backwards butscaixely to the 

 right. Length 0.25 inch, width 0.16 inch, 

 height 0.13 inch. 



Remarks. — This is at once distinguish- 

 .ed from the preceding by its proportions. 

 j9. rivularls differs in having the apex more 

 on one side, and one end distinctly wider 

 than the other. 



FAMILY NAIADES. 

 Genus Axodonta. 

 Generic Characters. — Shell eqnivalve, inequi- 

 lateral, transverse; hinge toothless; the two mus- 

 cular impressions remote ; lioament long. The 

 shell is usually very thin. Animal with the lobes 

 of the mantle entirely separate. 



Jlnodonta Benedictensis . — Lea. 

 Description. — Shell ovate-trapezoidal, 

 ;thin; epidermis coarsely striate, yellow- 



ish or greenish brown, usually with two 

 or three dark green raj's posteriorly, in 

 old shells of a very dark color, obscuring 

 the rays ; beaks rather sjuali, Vvrinkled, 

 approximate ; discs niodurately inflated ; 

 anterior side two thirds to one half as long 

 as the posterior ; hinge margin straight; 

 anterior and posterior margins straight 

 and divergentabove, below abruptly roun- 

 ded into tiie basal margin, which is mod- 

 erately curved throughout, except in old 

 shells, in which it is straijrht or even in- 

 curved in the middle. Dimensions of 

 two specimens: No. 1, length 4.5 inches, 

 he-ight 2.75 inches, width 1.7 inch; No. 

 2, length 3.S7 inches, height 2.5 inches, 

 width 1.5 inch. 



Re.marks. — It will \;2 seen in the abovf? 

 measurements, that the proportionate 

 length is subject to considerable varia- 

 tion, which affects only the posterior side, 

 and in part is a sexual distinction. This 

 species is abundant in lake Champlain, 

 but is not found elsewhere. It is much 

 larger than any other Anodonta in this 

 state. 



.Anodonta murginata . — S a y . 



Description. — Shell ovate, widest be- 

 low the beaks, thin ; epidermis yellowish 

 and greenish brown, with very irregular 

 stria? of £rrowth ; beaks rather prominent, 

 with numerous small wrinkles; discs mo- 

 derately inflated, flattened ; anterior side 

 about two fifths as long as the posterior ; 

 hinge margin curved ; posterior margin 

 slightly curved in a descent of one third 

 of the length of the shell, then rapidly 

 rounding into the basal margin, which is 

 nearly straight at and behind the middle ; 

 anterior margin regularly rounded . inte- 

 rior bluish. Length 3.8 inches, height 1.6 

 inch, width 1.15 inch. 



REMAr>KS. — This species may be most 

 easily distinguished from the ,Q. niidulata, 

 by the greater size and very minute wrin- 

 kles of the beaks, and the flattening of the 

 umbo. It has been found in Otter Creek 

 at Wallinorford. If it be not the .'2. mar- 

 ginata of Say, that species cannot novc 

 be recognized. It has been found more 

 abundantly in Massachusetts by Dr. 

 Gould, on whose authority I have given 

 it this name. 



Anodonta JJuviaiUis — Dm. win. 

 Description. — Shell oblong-ovate, wi- 

 dest behind the beaks, thin ; epidermis 

 smooth, yellowish, and brownish green, 

 olivaceous posteriorly and above, where 

 are a few obscure dark rays ; beaks quite 

 small, with numerous small wrinkles ; 

 discs moderately inflated, convex ; ante- 

 rior side between a third and a fourth as 

 long as the posterior ; hinge margin 



