MARINE MOLLUSCA OF THE UNITED STATES. 61 
Genus AMAUROPSIS, Morch. 
1. A. Isnanpica, Gmelin. Fig. 104. 
(Nerita.) Syst. Nat. 3675. 1790. 
Natica helicotdes, Johnston, Trans. Berw. Club, i. 69, 266. 1835. 
Natica canaliculata, Gould, Am. Journ. Sci., xxxviii. 197. 1840. 
Shell subglobose, rather ponderous, dingy-white, nearly smooth 
and somewhat glossy, covered with a dark gamboge-colored epi- 
dermis; whorls four, the upper portion of each turning before it 
joins the preceding whorl, so as to form a broad, shallow canal at 
the suture, and giving the spire a turreted appearance; aperture 
about two-thirds the length of the shell, nearly semicircular; lip 
sharp, a little spreading in front, the inner margin nearly a straight 
line, and overspread with a thick callus; interior white; umbilical 
Opening a mere slit, generally none. 
Length 27.5, diam. 18 mill. 
Resembles in shape Paludina ponderosa. 
Massachusetts northwards (Hur.). 
Genus SIGARETUS, Lamarck. 
Prodr. 77." 1799: 
H. and A. Adams, and others, use the generic name Catinus, 
Klein, in preference to that given by Lamarck, but Klein’s genus 
is named “Catinus lactis,’ and is, therefore, not admissible. 
1. C. PERSPECTIVUS, Say. Fig. 105. 
Am. Conch., iii. t. 25. 1831. 
Shell ovate, elongate, depressed. Surface with numerous im- 
pressed, transverse, slightly undulated lines, crossed by revolving 
strie which become obsolete beneath. Aperture more than three- 
fourths the entire area of the shell. Whorls three; spire de- 
pressed, smooth; suture distinct, but not deeply impressed. 
Milk-white, sometimes tinged with brown; within smooth and 
polished, and faintly iridescent. 
Length 37, of aperture 24 mill. 
New York, southwards. 
2. C. MACULATUS, Say. Fig. 106. 
Am. Conch., iii. t. 25. 1831. 
Shell with numerous transverse hardly undulated impressed 
lines and longitudinal wrinkles; spire scarcely prominent, slightly 
convex; whorls about three; suture a simple impressed line. 
