COMPENDIVM OF GENERIC DISTINCTIONS. 



621 



Genus. Sepiola.— Body short; tins on back and rounded. 

 Suckers in two rows or crowded on arms, fourrowson tentacles. 

 Many .seas. 



Family. SEPJADJE. — Shell chalky. Tentacles long and wide 

 at tins. 



Genus. Sepia. — Body oblong; tins on side, long as body. 

 Four rows of suckers on arms. Many seas. 



Family. SPIRALIDiE.— Shell spiral and delicate, divided 

 into many compartments connected by a siphuncle as in Tetra- 

 oranchiata. 



Genus. Spikula. — As family. Southern seas. 



Order. TETRABRANCHIATA.— Animal creeping, shell ex- 

 ternal and chambered. Eyes on footstalks, jaws chalky, arms 

 numerous. Branchiae four. 



Family. NAUTILIDJE.— Body-chamber large. Siphuncle in- 

 ternal. 



Genus. Nautilus. — Few whorls of shell. Warm and tropical 

 seas. 



Order. GASTEROPODA.— Sides not symmetrical. Broad 

 muscular foot under body. 



Sub-order. PROSOHRANCHIATA.— Abdomen largo and 

 protected by a large shell. Branchiae before the pulsating 

 vessel. 



Section. SIPHONOSTOMATA.-Shell spiral, aper- 

 ture notched or produced. Operculum horny. Gills placed ob- 

 liquely over back. 



Family. STROMBIDiE.— Shell with wide and deeply-notched 

 lip. Operculum claw-shaped and notched. Eyes large, on 

 footstalks; foot small and feeble. 



Genus. Strombus. — Spire short, aperture long, outer lip ex- 

 panded. Warm seas. 



Genus. Rostellaria. — Spire long and many-whorled. Pos- 

 terior canal running up spire. Warm seas. 



Genus. Pteroceras. — Outer lip formed into several long 

 claws. India and China. 



Family. MTJR.ICID2E. — Canal straight in front, none behind. 

 Eyes without footstalks. 



Genus. Murex. — Varices continuous, three or more rows. 

 Aperture rounded, beak mostly very long, canal partly closed. 

 Many seas. 



Genus. Triton. — Varices not continuous; lips toothed. Warm 

 seas. 



Genus. Raneli.a. — Two rows of continuous varices. Many 

 warm seas. 



Genus. Ptrula. — Pear-shaped; spire short, outer lip thin; 

 canal long and open. Warm seas. 



Genus. FascIOLARIA. — Shell long; canal open. Several ob- 

 lique folds in inner lip. Warm seas. 



Genus. Fusus. — Shell spindle-shaped, spire short, outer lip 

 thin; canal long and open. Warm seas. 



Family. BUCCINIDiE. -Shell with canal bent backwards, or 

 notched. 



Genus. Buccinitm. — Few and rounded whorls, aperture large, 

 canal reflected. Many seas. 



Genus. CoNCHOLEPAS. — Aperture very large, spire very 

 short. Central America. 



Genus. Harpa. — Aperture wide, and notched in front; spine 

 short; ribs numerous and regular. Warm seas. 



Genus. Purpura. — Spine short, aperture moderate and 

 notched in front; inner lip flattened. Shell streaked or tuber- 

 culated. Many seas. 



Genua. Macii.is. — Shell spiral and thin when young; pro- 

 longed when old into irregular tube, solid behind, lied Sea 

 and Mauritius. 



Genus. TereHRA. — Long, pointed, many whorls; aperture 

 small, canal sliort. Warm seas. 



Genus. 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. 



Genus. Cassis. — Shell swollen, varices irregular; spine sliort, 

 aperture long, outer lip toothed, canal recurved. Tropical 

 seas. 



Genus. Olivia. — Shell cylindrical and polished, spine short; 

 aperture long, narrow, and notched in front. Foot very large, 

 lobes of mouth meeting over shell. Warm seas. 



Genus. Columijei.la. — Aperture long and narrow, outer lip 

 thick and toothed. Warm seas. 



Family. CONID.?£.— Shell forming double cone; aperture 

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



Genus. Conus. — Shell tapering regularly; spire short and 

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

 warm seas. 



Family. VOLUTIDJE.— Shell turrctcd or convolute; aperture 

 notched in front; columella plaited obliquely. Foot very large. 



Genus. Mitra. — Spindle-shaped; spire sharp; aperture small. 

 Many seas. 



Genus. Voluta. — Shell swollen and thick; spire short; aper- 

 ture large. Warm seas. 



Genus. Cymba. — Nucleus large and globular, whorls few. 

 Rest like Voluta. Warm seas. 



Genus. Maiuiinella. — Spire very short; aperture truncated 

 in front; outer lip truncated when adult; columella plaited. 

 Warm seas. 



Family. CYPRJEIDJE. — Shell convoluted and enamelled. 

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

 Outer lip thickened. 



Genus. Cypr.ea. — Shell swollen; canals short; outer lip 

 ridged. Most seas. 



Genus. Ovulum. — Inner lip smooth. Rest like Cypraea. 

 Many seas. 



Seciim. HOLOSTOM ATA SEA SN AILS.- 



Shell spiral; edge of aperture entire. Animal \yith gills like 

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

 Operculum hard and shelly on exterior. 



Family. NATTCIDJE.— Shell globular; whorls few; spire 

 small and blunt; aperture semilunar. Animal with long pro- 

 boscis, 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. NERITIDiE.— Shell globular and thick; spire small; 

 aperture semilunar; outer lip sharp. 



Genus. Nerita. — Shell smooth or spirally grooved; outer lip 

 thickened; epidermis horny. Warm seas. 



Genus. Nekitixa. — Inner lip straight and toothed. 



Family. CERITHIADiE. —Shell long, spiral, many whorled; 

 aperture channeled in front. 



Genus. Ceritiuum. — Shell turrotod, faint varices; aperture 

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

 thickened. World-wide. 



