DIVISION. INVERTEBRATA. 



Animals without -vertebrae, true heart, or brain. 



CLASS, MOLLUSCS. 



Invertebrate animals with soft bodies, enclosed in a muscular skin Mostly with an 



univalve or bivalve shell. 



Sub-class. CEPHALOPODA. Two sides symmetrical. 

 Jaws powerful and vertical. Eyes large, on sides of head ; 

 cephalic ganglion (i.e. the knot of nervous matter which takes 

 the place of the brain) protected by cartilage. Arms set round 

 head. 



Order. DIBRAXCH I ATA. Eyes sessile and prominent ; 

 jaws horny ; arms with suckers. Two gills. Ink-gland 

 present. 



Section. OCTOPODA .Arms eight ; eyes fixed. 



Family. ARGON AUTID^E. Dorsal arms of female 

 webbed at tips, and secreting a delicate shell. Mantle sup- 

 ported in front by a single ridge on the funnel. 



Genus. ARGONAUTA. As family. Warm seas. 



Family. OCTOPODID.. Arms not webbed, united at 

 base by mantle. Two short styles in mantle instead of shell. 



Genus. CIRRHOTEUTHIS. Two fins on body. Arms united 

 nearly to tip ; suckers in single row. Northern seas. 



Section. DECAPODA Arms ten. Tentacles two. 

 Suckers on footstalks. Shell loose in mantle. 



Family. TEUTHIDjE. Body long; fins short and broad. 

 Shell horny. 



Genus. SEPIOLA. Body short ; fins on back and rounded. 

 Suckers in two rows or crowded on arms, four rows on ten- 

 tacles. Many seas. 



Family. SEPIAD^E. Shell chalky. Tentacles long and 

 wide at tips. 



Genus. SEPIA. Body oblong ; fins on side, long as body. 

 Four rows of suckers on arms. Many seas. 



Order. TETRABRANCHIATA. Animal creeping, shell 

 external and chambered. Eyes on footstalks, jaws chalky, 

 arms numerous. Branchiae four. 



Family. NAUTILID/E. Body-chamber large. Siphun- 

 cle internal. 



Genus. NAUTILUS. Few whorls of shell. Warm and tropi- 

 cal seas. 



Order. GASTEROPODA. Sides not symmetrical. 

 Broad muscular foot under body. 



Sub-order. PROSORRANCHIA TA. Abdomen large 

 and protected by a large shell. Branchiae before the pulsating 

 vessel. 



Section. SIPHONOSTOMATA.$\\e\\ spiral, aperture 

 notched or produced. Operculum horny. Gills placed obliquely 

 over back. 



Family. STROMBID^E. 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 

 expanded. Warm seas. 



Genus. ROSTELLARIA. Spire long and many-whorled. 

 Posterior canal running up spire. Warm seas. 



Genus. PTEROCERAS. Outer lip fonned into several long 

 claws. India and China. 



Family. MURICID/E. 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. RANELLA. Two rows of continuous varices. 

 Many warm seas. 



Genus. PYRULA. Pear-shaped; spire short, outer lip 

 thin ; canal long and open. Warm seas. 



Genus. FASCIOLARIA. Shell long; canal open. Several 

 ; oblique folds in inner lip. Warm seas. 



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

 thin; canal long and open. Warm seas. 



Shell with canal bent back- 



Family. BUCCINIDj*E.- 

 wards, or notched. 



Genus. BUCCINUM. 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 

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

 : culated. Many seas. 



Genus. MAGILUS. Shell spiral and thin when young ; pro- 

 longed when old into irregular tube, solid behind. Red Sea 

 and Mauritius. 



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

 small, canal short. Warm seas. 



Genus. EBURNA. When adult, inner lip spreads and cover* 

 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 

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

 cal seas. 



Genus. OLIVA. 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. COLUMBELLA. Aperture long and narrow, outer 

 lip thick and toothed. Warm seas. 



Family. CONIDJE. 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. VOLUTION. Shell turreted or convohite ; 

 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; 

 aperture large. Warm seat. 



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