CONCHIFEEA. 479 



O. cuneatiis was formally eaten by the Indians. At Mobile, 

 on the Gulf of Mexico, it is found in colonies along with Cyrena 

 CaroUnensis, burrowing 2 inches deep in banks of mud; the 

 water is only brackish, though there is a tide of 3 feet. Banks 

 of dead shells, 3 or 4 feet thick, are found 20 miles inland : 

 Mobile is built on one of these shell-banks. The road from 

 New Orleans to Lake Pont-chartrain (6 miles) is made of 

 Gnathodon shells procured from the east end of the lake, where 

 there is a mound of them a mile long, 15 feet high, and 20 — 60 

 yards wide ; in some places it is 20 feet above the level of the 

 lake. (Lyell.) 



LuTRARiA, Lamarck. Otter' s-shell. 



Tyjje, L. oblonga, Gmel. PI. XXL, Fig. 3. (= L. solenoides, 

 Lamarck). 



Shell oblong, gaping at both ends ; cartilage-plate prominent, 

 vith 1 or 2 small teeth in front of it, in each valve ; pallial 

 sinus deep, horizontal. 



Animal with closed mantle-lobes ; pedal opening moderate ; 

 foot rather large, compressed; siphons united, elongated, in- 

 vested with epidermis ; palpi rather narrow, their margins 

 plain ; gills tapering to the mouth. 



Distrihiition, 18 species. United States, Brazil, Britain, Medi- 

 terranean, Senegal, Cape, India, New Zealand, Sitka. 



Fossil, 25 species. Garb. — . United States, Europe. 



Eesembles Mya ; burying vertically in sand or mud, especially 

 of estuaries ; low water, 12 fathoms. L. rugosa, found living 

 on the coasts of Portugal and Mogador, is fossil on the coast 

 of Sussex. (Dixon.) 



Siih-genus, Vaganella, Gray. Mantle sinus, large, round; 

 interior ridges, of which two diverge from the hinge to the 

 ventral edge. 



Anatinella, G. Sowerby. 



Type, A. Candida, (Mya) Chemn. PI. XXIII. , Fig. 6. 



Shell ovate, rounded in front, attenuated and truncated be- 

 hind ; cartilage in a prominent si^oon-shaped process, with 2 

 small teeth in front ; muscular impressions iiTegular, the 

 anterior elongated ; pallial line slightly truncated behind. 



Bistrihutiou, 3 species. Ceylon, Philippines; sands at low 

 water. 



Family XYL — Tellenid^. 



Shell free, compressed, usually closed and equivalve ; cardinal 

 toeth 2 at most, laterals 1 — 1, sometimes obsolete ; muscular 



