THE NATURAL HISTORY SURVEY. 263 
105. Limnza catascopium Say, pl. xxxi, fig. 5. 
Limnea catascopium Say, Nich. Encycl., ed. 1, pl. ii, fig. 3, 1816. 
Limnea cornea V ALENCIENNES, Recueil d’Observ. Zool., etc., Vol. II, 
p. 251, 1883, 
Limnea sericata ZIEGLER, Rossmassler Iconog., Vol. I, p. 98, 1737. 
Limnea intertexta CURRIER, MSS., vide Bryant Walker, in letter. 
Shell: Rather solid, ovate, inflated; color light horn to 
blackish; surface dull to shining, lines of growth numerous, 
‘fine, crowded, wavy, crossed by numerous impressed spiral 
lines; apex small, rounded, chestnut colored; whorls’ five, 
rounded, subinflated, the last large and somewhat inflated; spire 
- sharp to obtuse, conic; sutures impressed; aperture roundly 
ovate, large, from half to three-fourths the length of the en- 
tire shell, rounded below; somewhat narrowed above; peris- 
tome thin, sharp, thickened by a light, whitish callus just within 
the edge; columella oblique, with a heavy plait across the mid- 
dle; the lower part of the columella has a flexure caused by 
the heavy plait; the lower part of the peristome and the whole 
of the columella is sometimes covered by a heavy coating of 
white, testaceous material, which is reflected over the umbili- 
‘cus, completely closing it. 
Length, 15.00; width, 7.50; aperture length, 8.00; width, 4.50 mill. 
a T2004 Ae 00> m “ COO SAN ore 
ee 15,00< - o%.*" 6.50 sf ts GOOr aia At 
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Animal, jaw, radula and genitaha not examined. 
Distribution: New England to Utah, British America to 
Virginia. 
Geological distribution: Pleistocene. 
Flatitat: In the larger lakes and rivers, attached to sticks, 
stones and débris. 
Remarks: Catascopium is readily distinguished by its large 
aperture, and well rounded whorls. The height of the spire 
varies, in some specimens being one-half the length of the 
aperture (var. pimguis) and in others they are about equal. 
In the typical form the spire is gracefully conical, and the 
aperture and lower part of the shell are evenly rounded. The 
only species with which this species can be confounded is 
Limnea palustris, but that species is generally larger, the spire 
is sharper and generally longer, and the surface is malleated, 
while catascopium is not. A comparison of the figures of the 
two species will suffice to separate them. Catascopium seems 
. 
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