558 MOLLUSCA 



N. {Tritia Risso) trivittata Say. Shell conical, with 7 whorls; 

 sutures impressed, with a shoulder below; surface with numerous longi- 

 tudinal and revolving creases dividing it into series of large granules; 

 foot bifurcate behind; color greenish-white, often with brown revolving 

 bands, white within; length 18 mm.; width 8 mm.: Florida to Gulf of 

 St. Lawrence; common. 



N. {Ilyanassa Stimpson) obsoleta Say (Fig. 877). Shell conical, 

 with 6 whorls, the lower one being large ; surface covered with numerous 

 longitudinal and revolving creases, giving it a reticular appearance; 

 foot not bifurcate behind ; margin of operculum not serrate ; color brown, 

 purple or black within; length 25 mm.; width 12 mm.: Gulf of St. Law- 

 rence to west Florida; the commonest snail south of Cape Cod. 



Family 4. BUCCINIDAE. 



Shell usually thick and ovate or pear-shaped, with a conical spire 

 and a large lower whorl; aperture usually large, ending below in a wide 

 notch or a short, wide siphonal canal; central tooth of radula with 5 

 to 7 cusps; laterals with 2 or 3: over 1,100 species. 



Key to the species of Buccinidae here described: 



Oi No distinct canal 1. Buccinum 



Oj Distinct canal 2. Neptunea 



1. Buccinum L. Whelks. Shell covered with a horny periostra- 

 cum; aperture with a wide notch at the lower side and about as long as 

 the spire: 30 species, in colder waters. 



B. undatum L. Shell with 6 whorls and grayish in color, with about 

 12 prominent crescentic or oblique longitudinal ridges, which disappear 

 towards the tip and are crossed by numerous raised revolving lines; 

 aperture oval, usually yellow, but sometimes white within; length 60 

 mm. ; width 35 mm. : New Jersey to Greenland, from low 

 to deep water; common north of Cape Cod; Europe, 

 where it grows larger than here, and is a common article 

 of food, and is also used extensively as bait for cod. 



2. Neptunea Bolton {Chrysodomus Swainson). Shell 

 fusiform, covered with a horny periostracum ; spire ele- 

 vated; aperture oval, shorter than the spire, with a short 

 canal, white or yellowish in color: circumpolar, about 15 

 species on the Atlantic coast, mostly in deep water. 



N. pygmsea (Gould) (Fig. 878). Shell with an elevated spire, with 

 6 whorls and a small, elongate aperture, ending below in a rather long 

 canal; periostracum hirsute; length 20 mm.: Long Island Sound to the 

 Gulf of St. Lawrence, in 10 to 640 fathoms. 



