EAST COAST MARINE SHELLS 



97 



GENUS RISSOINA Orblgny 1840 



RISSOINA BRYEREA Montagu. Shell solid, 

 somewhat shining, white or yellowish; 

 whorls seven, conspicuously ribbed. Length 

 5. 5 nun. 



Frequent upon both of the Florida 

 coasts and the Keys. 



PI. 37, Fig. 19 



Florida; West Indies 



RISSOINA CANCELLATA Philippi. Shell white; 

 ten convex whorls cancellated with sixteen 

 to eighteen upright ribs and four to five 

 revolving ridges, many ridges on base; out- 

 er lip strong, notch at base pronounced; a 

 faint encircling rib at base of shell. 

 Length 8 mm., diameter 3 mm. 



PI. 37, Fig. 17 



Florida Keys; West Indies 



RISSOINA CRESNELII Mlchaud. Shell white, 

 shining; whorls eight, slightly convex; 

 about fourteen strong ribs to each whorl 

 with interspaces which are scarcely spiral- 

 ly sculptured; oblique ridge at base of 

 shell. Length 3.5-4 mm., diameter 1.5 mm. 



PI. 37, Fig. 18 



Florida; West Indies 



RISSOINA DECUSSATA Montagu. A solid, white, 

 shining shell with about twelve flat whorls; 

 twenty-five to twenty-eight delicate ribs 

 crossed by fine spiral lines; outer lip 

 heavy, almost semi-lunar, canal indistinct. 

 Length 5-6 mm. 



PI. 37, Fig. 25 



Florida; West Indies 



RISSOINA FENESTRATA Schwartz. Solid, white; 

 twelve to fourteen longitudinal ribs to 

 each whorl which are crossed by spiral ones, 

 five on last whorl; lip varicose. Length 

 4.3 mm. 



Florida; West Indies 



RISSOINA LAEVIGATA C. B. Adams. Shell some- 

 what shining, white or pale amber color; 

 outer lip well thickened, often dentate; 

 nucleus of several whorls and peculiar 

 shape. Length 4 mm. Depth range 1-22 

 fathoms . 



Taken fresh after a September "blow" 

 near the North Inlet, Palm Beach, Florida. 



PI. 33, Fig. 6 



PI. 37, Fig. 16 



Cape Hatteras, North Carolina to 



Gulf of Mexico; West Indies 



GENUS ONOBA H. and A. Adams 1854 



ONOBA ACULEUS 'ould. 



PI. 71 Fig. 12 



Bay of Fundy to Long Island Sound 



Family Amnicolidae 



GENUS HYDROBIA Hartmann (Paludestrina 

 Orblgny 1840) 



HYDROBIA MINUTA Totten. A thin, smooth 

 shell with a blunt apex; suture distinct; 

 color varying from yellow-brown to iron 

 color when fresh; whorls five, surface fine- 

 ly striate. Length 3.5-4 mm. 



PI. 37, Fig. 12 

 PI. 71, Fig. 17 

 New England to Florida 



HYDROBIA SALSA Pilsbry. A gray or greenish 

 little shell; surface with lustre like dull 

 silk, finely striated; whorls 5.5. Length 

 3.1 mm. 



It is more broadly conic in shape 

 than H. mlnuta, the sutures less deep, aper- 

 ture and last whorl larger. The first 

 specimens were collected at Cohasset, Mass- 

 achusetts living with H. mlnuta and Odo- 

 stomia impressa. It delights in salt-marsh 

 pools. 



Unfigured 



Rowley, Massachusetts to Ocean Coun- 

 ty, New Jersey 



Family Litiopidae 



Shell minute, pointed; slight notch 

 in front of aperture; outer lip thin and 

 simple, inner one reflected; operculxim spi- 

 ral. 



GENUS LITIOPA Range 1828 

 (SIMPLE MOUTH SHELLS) 



LITIOPA BOMBYX Rang (L, melanostoma Rang). 

 About nine whorls, slightly convex; color 

 light brown, often bordered internally with 

 black. Length 5 mm. 



Pilsbry writes "To ascend through 

 the water this little pelagic animal emits 

 an air bubble enclosed in a glutinous se- 

 cretion, which draws out a thread as it 

 rises, and finally attaches itself to float- 

 ing seaweed." 



Fresh seaweed, taken upon the beach, 

 often contains this shell. By placing the 

 weeds in fresh water the living shells im- 

 mediately detach themselves and drop to the 



