552 MOLLUSCA 



(propodium and mesopodium) which projects ventrally and often bears 

 a sucker, and a tail (metapodium) which projects posteriorly, and in 

 some forms bears an operculum; head large, bearing a pair of tentacles 

 with large eyes on short stalks at their base; the principal viscera form 

 a sort of nucleus, often brightly colored, dorsally situated and covered, 

 in most cases, by a transparent shell; sexes separate: about 60 species, 

 all of which live on the high sea, often in large schools, in tropical and 

 subtropical regions, eating fishes, Crustacea, and other small animals; 



2 families. 



Key to the families of Heteropoda : 



Oi Shell much too small to contain the animal and sometimes absent. 



1. ' Pterotracheidae 



03 Shell multispiral, containing the bodj' 2. Atlantidae 



Family 1. PTEEOTRACHEIDAE. 



Body elongate, cylindrical, transparent, naked or with a small, trans- 

 parent, conical, cap-shaped shell which covers the small nucleus alone, 

 and from which projects the ctenidium: 4 genera and about 30 species. 



Fig. 866 Fig. 867 



Fig. 865 — Carinarm meditetranea (Cambridge Natural History). 1, sucker; 2, fin; 



3, shell; 4, gill; 5, tentacle. Fig. Him — Atlanta peroni (Leunis). 



Fig. 867 — Eulima oleacea (Verrill). 



Carinaria Lamarck. Small conical shell present: 8 species in 

 tropical and subtropical seas; 1 species on the South Atlantic coast. 



C. mediterranea Peron and Lesueur (Fig. 865). Body 20 cm. long 

 or less; snout violet; foot red: New Jersey to Florida; West Indies; 

 Mediterranean Sea. 



Family 2. ATLANTIDAE. 



Shell spiral and discoid and large enough to receive the entire 

 body: 22 species, in 2 genera. 



1. Atlanta Lesueur. Shell small, thin, compressed, with a promi- 

 nent keel on the periphery; aperture narrow, with a deep notch at the 

 keel; operculum ovate: 18 species, 6 on the South Atlantic coast. 



A. peroni Les. (Fig. 8G6). Length 8 cm.: New Jersey to Texas; 

 West Indies; Mediterranean. 



