FAMILY LIMNIAD.E LIMNEA. 67 



GENUS LIMNEA. Lamarck. 



Animal spiral, elongated or oval. Head with two flattened triangular tentacles, with the eyes 

 at their internal base. Mouth surmounted by a free thin movable appendage. Foot oval, 

 bilobed in front, contracted behind. Breathing orifice on the right side, narrow, oblong, 

 and covered by a fleshy appendage which borders it beneath : vent near it. Generative 

 organs distant : the male under the right tentacle ; female near the breathing orifice. Sexes 

 united in the same individual. Shell thin, dextral, oval, elongated ; spire more or less 

 acute and elongated : aperture longer than wide, oval, occasionally very large ; lip thin ; 

 an oblique fold on the columella. 



Obs. The animals of this genus inhabit fresh water streams, or their vicinity, feeding on 

 aquatic animalculae. The American species have been carefully studied and beautifully illus- 

 trated bv Mr. Haldeman. 



LlMNEA CATASCOPIUM. 



PLATE V. FIG. 80. 



(STATE COLLECTION.) 



Lymnea calascopium. Say, Nich. Ency. Vol. 4, p. 2, fig. 3 ; Ara. Conchology, pi. 55, fig. 2. 



L. pinguis.' var. Id. Jour. Acad. Nat. Sciences, Vol. 2, p. 123. 



L. decollata. Adams, Bost. Jour. Nat. Hist, ride Haldemani. 



L. catascopium. Gould, Invertebrata of Massachusetts, p. 223. 



L. id. Haldeman, Monog. of the Limniades, No. 3, p. 6, pi. I, figs. 1 - 12. 



Description. Shell smooth and polished, oblong-ovate. Whorls four or five, convex, with 

 wrinkled incremental lines, and rapidly tapering to an acute apex : body-whorl large and ven- 

 tricose : spire shorter than the aperture : aperture ovate. Lip simple, thick, and regularly 

 curved : pillar-lip concave, with a distinct fold. 



Color. Yellowish horn or blackish. Animal yellowish brown, minutely punctate with light 

 yellowish : foot rounded behind. 



Diameter, 0-2-0-4. Height, 0-5-0-7. 



I have followed Mr. Haldeman in uniting the pinguis of Say with the above. Common in 

 the western district of this State. It ranges from Massachusetts to Delaware, and west- 

 wardly through the Northwest territory. 



