Naticidae 123 



ture reversed in relief; columella flexuose with a strong oblique 

 fold well within aperture; base and body whorl below periphery- 

 engraved with clear-cut spiral grooves; operculum pale brown. 

 Associated with other Odostomias. 



All members of this family have shells with reverse apex but animal 

 is dextral, specimens of veligers are easily recognized in the plankton. 

 Known eggs are either enclosed in irregular gelatinous mass or in small 

 lenticular capsules. Eggs 0.24-0.35 mm. diameter. Very thin-walled 

 lens-shaped capsules attached by the lower surface. Pour to 8 ova in 

 each capsule. The young hatch with transparent, colorless, sinistral shell, 

 of 1 whorl. Veliger has bilobed velum. — Marie Lebour. 



Family NATICIDAE 



The family Naticidae is one of the subdivisions of the Mollusca 

 called Platypoda, which means "broadfoot". The propriety of the 

 name is evident when individuals of the species Natica, Polinices, 

 or Sinum are seen ploughing through the sandy sea bottom in quest 

 of prey. 



Characteristic of the group is the highly distensible oval foot 

 which overflows and almost conceals the entire shell when the animal 

 is expanded. A well-developed cephalic disc, or propodium, is re- 

 flected over the head of the animal and the anterior border of the 

 shell. The sense of smell and touch are apparently keen, but eyes are 

 absent or subtegumental. The radula is well developed in all species 

 of the Naticidae, and by its use a neat round hole is drilled through 

 the umbonal region of the shells of bivalve mollusks which consti- 

 tute the food of this voracious and predatory race. 



The shells are subglobular or depressed and auriform, the body 

 whorl is much expanded and the aperture correspondingly large, not 

 canaliculate, with a simple, sharp outer lip. 



The group has a wide distribution from Arctic to Antarctic 

 seas. 



Genus NATICA Scopoli, 1777 

 Natica2i7 caurena (Linne) PI. 24, figs. 165a, b 



Alt., up to 45 mm. Shell subglobular, smooth; adult specimens 

 thick; apex small, spire depressed, body whorl expanded; pale and 

 deep fawn color disposed in revolving bands, with zigzag markings 

 of dark brown, strongest over upper part of shell; base white; thin, 



-1" Lat., natica, buttock. 



