CONCHIFERA. 309 



short, partly united ; foot very thick, tongue-shaped, pointed; gills unequal, 

 the outer short and narrow ; palpi large, triangular, pointed. 



Distr. 1 sp. N. Orleans (3 other sp. ? Mazatlan, California; Moretori 

 B. Australia. Petit.) 



Fossil, 1 sp. Miocene . Petersburg, Virginia. 



G. cuneatus was formerly eaten by the Indians. At Mobile, on the Gulf 

 of Mexico, it is found in colonies along with Cyrena Carolinensis, burying 

 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 pro- 

 cured 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. 



Type, L. oblonga, Gmel. PL XXI. fig. 3. (= L, solenoides, Lam.) 



Shell oblong, gaping at both ends ; cartilage-plate prominent, with 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, invested with epidermis ; palpi 

 rather narrow, their margins plain ; gills tapering to the mouth. 



Distr. 18 sp. U. States, Brazil, Brit. Medit. Senegal, Cape, India, N. 

 Zealand, Sitka. 



Fossil, 10 sp. Miocene U. States, Europe. 



Resembles My a ; burying vertically in sand or mnd, especially of estu- 

 aries ; low- water, 12 fms. L. rugosa is found living on the coasts of Por- 

 tugal and Mogador, fossil on the coast of Sussex. (Dixon.) 

 ANATINELLA, G. Sowerby. 



Type, A. Candida, (Mya) Chemn. PL XXIII. fig. 6. 



Shell ovate, rounded in front, attenuated and truncated behind ; cartilage 

 in a prominent spoon-shaped process, with 2 small teeth in front ; muscular 

 impressions irregular, the anterior elongated ; pallial line slightly truncated 

 behind. 



Distr. 3 sp. Ceylon, Philippines ; sands at low- water. 



FAMILY XVI. TELLINIDJE. 



Shell free, compressed, usually closed and equivalve ; cardinal teeth 2 at 

 most, laterals 1 1, sometimes obsolete; muscular impressions rounded, 

 polished; pallial sinus very large; ligament on shortest side of the shell, 

 sometimes internal. Structure obscurely prismatic- cellular ; prisms fusi- 

 form, nearly parallel with surface, radiating from the hinge in the outer 

 layer, transverse in the inner. 



