MARINE MOLLUSCA OP THE UNITED STATES. 6l 



Genus AMAUROPSIS, Morch. 



1. A. Islandica, Gmelin. Fig. 104. 

 (Nerita.) Syst. Nat. 3675. 1790. 

 Natica helicoides, Johnston, Trans. Berw. Club, i. 69, 266. 1835. 

 Natica canaliculata, Gould, Arn. Journ. Sci., xxxviii. 197. 1840. 



Shell subglobose, rather ponderous, dingy-white, nearly smooth 

 and somewhat gloss} 7 , 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 21.5, diam. 18 mill. 



Resembles in shape Paludina ponderosa. 



Massachusetts northwards (Eur.). 



Genus SIGARETUS, Lamarck. 

 Prodr. 77. 1799. 

 II. and A. Adams, and others, use the generic name Cat inns, 

 Klein, in preference to that given by Lamarck, but Klein's genus 

 is named "Catinus ladis," 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 

 stria?, 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. 



