554 MOLLUSC A 



T. elegans Verrill (Fig. 8G8). Whorls rounded, with numerous 

 longitudinal ribs and fine revolving grooves; color light yellow; length 

 9 mm.; width 2.5 mm: Massachusetts Bay to Florida, in 

 shallow water. 



T. interrupta (Totten). Shell very slender and 

 pointed, with 8 or 10 convex whorls, on which are 20 to 

 30 ribs crossed by about 14 revolving lines: Cape Cod to 

 South Carolina, in shallow water; common. 

 Turboniila 2. Odostomia Fleming. Shell minute, elongate, con- 



(Verruf). i^al, thin; aperture ovate; columella with an oblique 



fold: 100 species; cosmopolitan. 

 Key to the species of Odostomia here described : 



Ci Surface smooth. 



&i Color dark brown O. FUSCA 



h. Color glossy white O. trifida 



63 Color greenish with a line under the suture O. bisutubalis 



aa Surface granulated O. seminuda 



0. bisuturalis (Say). Shell conical, smooth, light green; periostra- 

 cum brown, with a single revolving line below the suture; length 5 mm.; 

 diameter 2.5 mm.; 6 whorls: Massachusetts Bay to New Jersey; common 

 under stones. 



O. fusca (Adams). Shell elongate, rather blunt, dark brown, glossy, 

 with 6 or 8 whorls ; 6 mm. long ; 1.8 wide ; umbilical indentation present : 

 Cape Cod to New Jersey, in shallow water; common. 



O. trifida (Totten). Shell elongate; apex acute; 

 whorls 8, flat, with about 6 revolving lines; color white; 

 length 5 mm. ; width 2 mm. : Massachusetts Bay to New 

 Jersey, in shallow water; common. 



'^ ' ' Fig. 869 



0. seminuda (Adams) (Fig. 869). Shell with an Odostomia 



seminuda 



acute apex, 6 or 7 whorls, with coarse revolving lines ■ (Verriii). 

 crossed by longitudinal ones, giving the surface a granu- 

 lated appearance; color glossy white; length 4 mm.; width 2 mm.: 

 Massachusetts Bay to west Florida; common in shallow water. 



Division 4. RACHIGLOSSA. 



Radula long and narrow, w^th 3 longitudinal rows of teeth (Fig. 

 870), a central and two lateral, each tooth, in most species, consisting 

 of a base and several cusps; proboscis long and retractile; siphon dis- 

 tinct and usually long; operculum usually present, and always horny 

 and non-s]nral; shell spiral, usually thick, often with tubercles or 

 spines; aperture elongate, prolonged below to fonn a siphonal canal: 

 12 families, marine (excepting a few species) ; carnivorous, 



