COMPENDIUM OF GENERIC DISTINCTIONS. 



785 



Family. BTTCCINID-ffi. Shell with canal pent backwards, 

 or notched. 



Genus. BPCOINUM. Few and rounded whorls, aperture 

 largo, canal reflected. Many seas. 



Genus. CONCHOLEPAS. Aperture very large, spire very 

 short. Central America. 



Genus. HABPA. Aperture wide, and notched in front ; 

 s^iine short ; ribs numerous and regular. Warm seas. 



Genus. PUKPURA. Spine short, aperture moderate and 

 notched in front ; inner lip flattened. Shell streaked or 

 tuberculated. Many seas. 



Genus. MAGILUS. Shell spiral and thin when young; 

 prolonged when old into irregular tube, solid behind. Red 

 Sea and Mauritius. 



Genus. TEREBRA. Long, pointed, many whorls ; aperture 

 small, canal short. Warm seas. 



Gemis. EBURNA. When adult, inner lip spreads and 

 covers umbilicus. Substance solid and smooth. 



Genus. DOLIUM. Shell rounded, spirally furrowed; 

 spire small, aperture very large. Warm seas. 



Genns. CASSIS. Shell swollen, varices irregular; spine 

 short, aperture long, outer lip toothed, canal recurved. 

 Tropical seas. 



Genus. OLIVA. Shell cylindrical and polished, spine 

 s-Lort ; aperture long, narrow, and notched in front. Foot 

 very large, lobes of mouth meeting over shell. Warm seas. 



Genus. COLUMBELLA. Aperture long and narrow, 

 outer lip thick and toothed. Warm seas. 



Family. CONID^E. Shell forming double cone ; aperture 

 long and narrow ; outer lip notched near or at suture. 



Genus. CONUS. Shell tapering regularly ; spire short 

 and many-whorled ; notch of outer lip at suture. Tropical 

 and warm seas. 



Family. VOLUTID.ffi. Shell turreted or convolute ; 

 aperture notched in front ; columella plaited obliquely. 

 Foot very large. 



Genus. MITRA. Spindle-shaped ; spire sharp ; aperture 

 small. Many seas. 



Genus. VOLDTA. Shell swollen and thick ; spire short ; 

 aperture large. Warm seas. 



Genus. CYMBA. Nucleus large and globular, whorls few. 

 Rest like Voluta. Warm seas. 



Genus. MARGINELLA. Sj ire very short ; aperture 

 truncated in front ; outer lip truncated when adult ; colu- 

 mella plaited. Warm seas. 



Family. CYPR.ffiID.ffi. Shell convoluted and enamelled. 

 Spire not visible ; aperture narrow, with a channel at each 

 end. Outer lip thickened. 



Genus. CYPU^A. Shell swollen; canals short; outer 

 lip ridged. Most seas. 



Genus. OVULUM. Inner lip smooth. Rest like Cyprsea. 

 Many seas. 



Section. HOLOSTOMATA (SEA SNAILS). 



Shell spiral ; edge of aperture entire. Animal with gills 

 like combs or feathers set across back on to neck. No siphon. 

 Operculum hard and shelly on exterior. 



. Family. NATICID.33. Shell globular ; whorls few ; spire 

 small and blunt ; aperture semilunar. Animal with long 

 proooscis, and large foot and mantle. 



Genus. NATICA. Shell thick and smooth; umbilicus 

 large ; callus spiral. Animal without eyes ; front of foot 

 and sides with large lobes. 



Genus. NATICELLA. Aperture very wide. 



Family. NERITID.ffi. Shell globular and thick ; spire 

 small ; aperture semilunar ; outer lip sharp. 



Genus. NERITA. Shell smooth or spirally grooved ; outer 

 lip thickened ; epidermis homy. Warm seas. 



Geniia. NERITINA Inner lip straight and toothed. 

 3. 



Family. CEEITHID5!. Shell long, spiral, many- 

 whorled ; aperture channeled in front. 



Genus. CERITHIUM. Shell turreted, faint varices ; aper- 

 ture small, with twisted canal in front ; outer lip expanded ; 

 inner lip thickened. World-wide. 



Genus. APOKRHAIS. Spire long, many-whorled, and 

 tuberculated. Short canal in front of narrow aperture. 

 Outer lip expanded, with finger-like projections. Many seas. 



Family. TTIRRITELLID^!. Shell spiral or tubular; 

 upper part partitioned off. 



Genus. TURRITELLA. Shell long, many-whorled, striped 

 spirally ; aperture rounded with thin edge. Many seas. 



Genus. VERMETUS. Shell tubular and irregular ; several 

 partitions in tube ; aperture round. Many seas. 



Genus. SILIQUARIA. Shell tubular, with longitudinal 

 slit. Warm seas. 



Genus. SCALARIA. Shell turreted, many-whorlod, with 

 many transverse ribs ; aperture round. Most seas. 



Family. LITORINID.ffi. Shell spiral, opaque ; aperture 

 rounded. 



Genus. LlTORlNA. Shell thick, few whorls ; outer lip 

 sharp. Most seas. 



Genus. SOLARIUM. Shell target-shaped, flattened ; um- 

 bilicus very deep. Warm seas. 



Genus. PHORUS. Shell concave beneath ; flattened 

 margins to whorls, often with stones and shells attached ; 

 aperture oblique ; outer lip very thin. Warm seas. 



Genus. TRUNCATELLA. Shell small, cylindrical ; aper- 

 ture oval and entire. Most seas. 



Family. PALTTDINID.ffi. Shell globular or conical ; 

 epidermis thick ; aperture round ; operculum hard. Muzzle 

 broad ; tentacles long and slender ; eyes on short footstalks. 



Genus. AMPULLARIA. Whorls round ; operculum horny. 

 Muzzle long ; neck with lappet on each side, forming a 

 siphon. Northern Hemisphere. 



Family. TTIRBINID^!. Shell spiral, pearly inside. 



Genus. PHASIANELLA. Shell long and polished ; whorls 

 convex ; aperture oval and not pearly ; outer lip thin. 

 Many seas. 



Genus. TROCHUS. Shell pyramidal, base flat, many- 

 whorled ; aperture pearly inside ; outer lip thin. World- 

 wide. 



Genus. DELPHINULA. Shell shield-like, flattened, few- 

 whorled, rough on exterior ; aperture round and pearly. 

 Warm seas. 



Family. HALIOTID^B. Shell spiral or ear-shaped ; aper- 

 ture very large and pearly ; outer lip notched or perforated. 



Genvto. HALJOTIS. Shell ear-shaped; spire small and 

 flat ; outer angle perforated with a row of holes. Most seas. 



Genus. STOMATIA. Outer lip furrowed, not pierced. 

 Warm seas. 



Genus. JANTHINA. Shell spiral, thin, and translucent, 

 few-whorled ; aperture squared ; lip very thin. Vesicular 

 float attached to foot. Atlantic. 



Family. FISSTTRELLID.. Shell conical and limpet- 

 shaped, front margin notched or tip perforated. 



Genus. FISSURELLA. Shell oval, tip perforated, surface 

 radiated. Most seas. 



Genus. PARMOPHORUS. Shell long and flattened, front 

 edge arched. Warm seas. 



Family. CALYPTRffiID.ffi. Shell limpet-like, interior 

 often with shelly process. Mott seas. 



Genus. CALYPIR^EA. Shell conical, edge irregular, cup- 

 shaped process in interior. Most se.'ts. 



Genus. PILEOPSIS. Shell conical ; apex spirally re- 

 curved ; aperture rounded. Most seas 



