474 LIMNiEIDj:. 



LimncBus catascop'mm, Haldeman, part, Mon. 52, pi. 14, figs. 1 -3 (1842). 

 Limmeus decollutus, Kustek, in Chemn. 2d ed. 45, pi. 8, tigs. 11-14. 



Shell very ventricose, rather thick, sub-ovate or sub-rotund, in 

 outline an irregular rhomboid ; epidermis of an olivaceous-green 

 color, rather thin, deciduous ; whorls two to three ; spire 

 F>R. <2o. ^^g^,y short, generally decollated ; whole surface gen- 

 erally ratlier rough ; striaa of growth coarse and fine 

 alternately ; transverse striee on the body whorl sparse, 

 interrupted, sometimes obsolete ; body whorl composes 

 almost the whole shell ; aperture very large, sub-cam- 

 panulate ; its length is very little greater than the 

 breadth, and occupies more than two thirds the length 

 of the shell ; labrum rather thin, simple ; fold of the columella very 

 prominent. Length, six tenths of an inch ; breadth, five tenths of 

 an inch ; height, four tenths of an inch. 



Animal dingy mouse-color, with a slight tinge of purple, covered 

 with numerous microscopic, elongated white spots on every visil)le 

 part of the surface, including the mouth and tentacula ; foot of a 

 chocolate color, rather broad, length rather greater than the aper- 

 ture ; habits sluggish. Cabinets of the Bost. Soc. N. H., Dr. Gould, 

 S. S. Haldeman, J. G. Anthony, J. W. Mighcls, and C. B. Adams. 

 Unity, Maine, discovered by Dr. Millikcn of that town, to whom 

 we are indebted for specimens. 



This odd but interesting shell is readily recognized by its rhom- 

 boidal aspect, wide aperture, and rather rough and distorted appear- 

 ance. It is allied to L. catascopium, Say, but is distinct from that 

 shell by having less whorls by two, and a much shorter spire ; by 

 being wider, and its divergence greater by more than thirty degrees. 

 By some it has been supposed to be identical with L. emarg-inata, 

 Say. This is impossible. L. emarginata is much more cylindrical, 

 the divergence of its spire is scarcely half as great as that of our 

 shell ; it is much thinner, and has at least two more volutions. Our 

 shell is also destitute of the " deep emargination " which distin- 

 guishes L. emarginata. {Mighels and Adams.') 



Found around Lake of the Woods, in Maine and Connecticut. 



Limnsea ampla. 



Shell large, inflated, sub-oval, rather thin, obscure olivaceous-green color; whorls 

 five, convex; suture deep; aperture oblong, occupying ratlier more than two 

 thirds the length of the shell; columella-fold very prominent; umbilicus open and 

 very deep. 



