LIMN^A. 35 



characters under the name of Limnarn chalybea, in Silliman's .journal, 

 XXXIII, 19(5. But as it has not heeu found in any other place, I am now 

 disposed to regard it as a strongly marked local vaiiety of L. columella. 

 It is very possibly such a shell to which Mr. Say alludes in the Journ. 

 Ac. Nat. Sc. II, 1G7, as L. columella, var. a., small, black, from Cold 

 Water Creek, Missouri. {Gould.) 



Liransea navicida, of Valenciennes, whose description follows, 

 is said to be a form of L. columella, by Haldeman and Gould, 

 and also by Ferussac (Bull. Zool. p. 35, 1835) and Kiister. I 

 have seen no specimen or figui'e of it. 



Limnaca navlcula, Valenciexnes. — Shell oval, pointed, subdiaphanous, 

 whirls four, substriate. The last whirl is four times as long as the three 

 others. The aperture is large and gaping, its length equalling two-thirds 

 the shell's length. Shell very thin, slightly transpanent. Color grayish- 

 yellow. Length 10 lines. 



Hab. Environs of Philadelphia. {Valenciennes.) 



Finally, an examination of the specimens from which Mr. Lea 

 drew his descriptions of Limnsea strigosa, coarctata, and casta, 

 have convinced me of their identity with L. columella. In the 

 case of the second species Haldeman agrees with me, he makes 

 no mention of the others. Mr. Lea's descriptions are copied 

 below, and a figure given of each of the three forms, drawn from 

 his types. 



Limnsea strigosa, Lea. — Shell long-oval, somewhat oblique, diaphanous, 

 striate, horn-colored, thin, imperforate ; spire short ; sutures 

 impressed ; whirls five, somewhat convex ; aperture ovate. ^ig* 41. 



Hab. Near Cincinnati, Ohio. T. G. Lea. My cabinet and 

 cabinet of T. G. Lea. Diam. .38, length .75 of an inch. 



This is a very thin fragile species, somewhat resembling L. 

 columella, Say, but may at once be distinguished from that 

 species by its longer spire and less inflated body whirl. It is 

 allied to L. coarctata, herein described ; differing, however, in 

 being more oblique, and in having the whirls more inflated. 

 The aperture is about three-fourths the length of the shell, and acutely 

 angular above. (Lea.) 



Limnsea coarctata, Lea, is also referred to L. macrostoma, 

 by Kiister, I. c. Mr. Lea's description here follows, with a draw- 

 ing of his original specimen. 



Limnsea coarctata. Lea. — Shell fusiform, very thin, obsoletely striate, 

 diaphanous, horn-color, imperforate ; spire short, pointed ; sutures slightly 

 impressed ; whirls four, rather flattened ; aperture large, ovate. 



