622 



COMPENDIUM <)F GENERIC! DISTINCTIONS. 



Genus. Aporrhais. — Spire long, many-whorled, and tuber- 

 culated. Short canal in front of narrow aperture. Outer lip 

 expanded, with finger-like projections. Many seas. 



Family. TURRITELLIDJE. — 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. Siltquaria. — Shell tubular, with longitudinal slit. 

 Warm seas. 



Genus. Sew, aria. — Shell turreted, many - wnorled, with 

 many transverse ribs; aperture round. Most .seas. 



Family. LITORINIDJE. — Shell spiral, opaque; aperture 

 rounded. 



(t'rinif. Litorin'a. — Shell thick, few whorls; enter lip sharp- 

 Must seas. 



Genus. Solarium. — Shell target-shaped, flattened; umbilicus 

 very deep. Warm seas. 



Genus. PHORUS. — Shell concave beneath; flattened margins 

 to whorls, often with stones and shells attached; aperture 

 oblique; miter lip very thin. Warm seas. 



Genus. Truncatella. — Shell small, cylindrical; aperture 

 oval and entire. Most seas. 



Family. PALTJDINID.2E. (See page 336, Apple-Snails.)— 

 Shell globular or conical; epidermis thick; aperture round; oper- 

 culum hard. Muzzle broad; tentacles long and slender; eves 

 on short footstalks. 



Genus. AmPULLaRIA. — Whorls round; operculum horny. 

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

 Northern hemisphere. 



Family. TURBINIDJE.— Shell spiral, pearly inside. 



Genus. PhasiaNella. — Shell long and polished; whorls eon- 

 vex; 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. Delphixula. — Shell shield-like, flattened, few- 

 whorled, rough on exterior; aperture round and pearly. Warm 

 seas. 



Famity. HALIOTIDJE— Shell spiral or ear-shaped; aperture 

 very large ami pearly; outer lip notched or perforated. 



Genus. IIai.iotis. — Shell ear-shaped; spire small and flat; 

 outer angle perforated with a row of hides. Most seas. 



Genus. Stomatia. — Outer lip furrowed, not pierced. Warm 



seas. 



Genus. Janthtn'a. — Shell spiral, thin and translucent, few- 

 wborled; aperture squared; lip very thin. Vesicular float at- 

 tached to foot. Atlantic. 



Family. FISSURELXIDiE.— Shell conical and limpet-shaped, 

 front margin notcbed 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. CALYPTR.7EIDJE.— Shell limpet-like, interior often 

 with shelly process. Most seas. 



Genus. C.vl.YPTB EA. — Shell conical, edge irregular, enp- 

 shaped process In interior. Most seas. 



Gi'lMS. I' 1 1 . 1 ; ii ] •< I s . — SI i e 1 1 conical; apex spirally recurved; 

 aperture rounded. Most seas. 



Family. PATELXLDJE. —Shell conical; apex turned forwards. 



Genus. Patella. — Shell oval, interior smooth; apex nearly 

 central. World-wide. 



Family. DENTALIDJE.— Shell tubular, curved, regular, open 

 at each end, tapering from mouth; aperture circular. 



Genus. DeN'TALIUM. — As family. Most .seas. 



Family. CHITONIDJE.— Shell ( posed of eight overlapping 



plates, lodged in a leathery mantle, each plate with a process 

 from its front edge. 



Genus. Chiton.— As family. World-wide. 



Genus. CHITONErxos. — Border velvety, exposed portions oi 

 the plate small. Hot seas. 



Onlcr. PULMONIFERA — Foot broad. Breathing organ a 

 simple chamber lined with network of respiratory vessels. 



Section. 1NOPERCU LATA. -Without operculum. 



Family. HELICmiE.— Shell external. Animal with four re- 

 tractile tentacles, upper pair largest and having eye -specks at 

 tips. Foot distinct; body spiral. Respiratory aperture on right 

 side, under e.lge of shell. Mouth with horny-toothed upper 

 mandible. 



Genus. Helix. — Aperture of shell transverse, oblique, 

 rounded, or semilunar; margins distinct. Animal with long 

 foot pointed behind. World-wide. 



Genus. Bulimus. — Shell oblong or turreted; longitudinal 

 edges of aperture unequal; columella entire. Animal like 

 Helix. Warm seas. 



Genus. Pupa, — Shell oblong or cylindrical; aperture rounded. 

 Animal with short foot, pointed behind. World-wide. 



Family. LIMACIDJE — Shell small or rudimentary, internal, 

 or concealed by mantle, placed over respiratory cavity. Animal 

 long; foot not distinct. 



Genus. LlMAX. — Shell internal, oblong, edge membranous. 

 Foot very long; mantle shield-shaped ; head and tentacles re- 

 tractile. World-wide. 



Genus. TestaCELLA.— Shell small, ear-shaped at end of body. 

 Back of animal with two long furrows, from which others 

 ramify. Many parts of world. 



ft nits. Ariiin.— Shell oval, or made of chalky granules. Tail 

 rounded, with gland at tip. Most parts of world. 



Family. LIMNJ£ID.ffi:. -Shell large and thin, lip sharp. 

 Muzzle short and wide; eyes at base of tentacles; mouth with 

 upper mandible. 



Genus. LlMN.EA. — Shell spiral, rather long, last whorl very 

 wide; aperture rounded in front. Tentacles triangular. Most 

 parts of w orld. 



Genus. Physa.— Spiral to left, and polished. Tentacles long 

 and slender; vA'^i- of mantle with a deep fringe. 



Genus. PlaXORBIS. — Shell flattened, many whorls; aperture 

 semilunar. Foot round and short; eyes at inner base of tenta- 

 cles. 



Section. OPERCU LATA. -With an operculum. 



ihilrr. OPISTHOBRANCHIATA.— Shell small or absent. 

 Branchiae towards end of body. 



Sub-order. TECTI-BRANCHIATA— Gills covered by shell 

 or mantle. 



Family. BULLIDJE. -Shell rounded, thin; spire small; aper- 

 ture long, rounded, and waved in front. Animal investing shell; 

 disc-like head; eyes none, or in disc. One gill on right of back. 

 Edge of mantle overlapping shell. 



Genus. Bulla.— Shell oval, swollen, partly invested by 

 annual; aperture larger than shell. Head-disc two-lobed be- 

 hind. Warm and hot seas. 



