LINGULA. CONCHIFERA. 75 



Gen. 1. LINGULA, Lam. Patella, Lin. 

 Shell subequivalve, flattened, oval-oblong, truncated at the sum- 

 mit ; slightly pointed at the base, elevated on a fleshy ten- 

 dinous pedicle fixed to marine bodies ; hinge without teeth. 



L. anatina, Lam. (P. unguis, Lin.) Shell greenish, like the hill 

 of a duck ; pedicle cylindrical. From two to four inches long. In- 

 habits Indian seas Rumph. Mus. pi. 40,, fig. L. 



Gen. . TEREBRATULA, Lam. 



Shell inequivalve, regular, subtrigonal, attached to marine bo- 

 dies by a short tendinous pedicle ; the larger valve with a pro- 

 jecting hook, often bent, pierced at its summit by a round 

 hole or notch ; hinge with two teeth ; and two osseous pro- 

 cesses rising from the disk of the smaller valve. 



This genus comprehends a great number of species, the greater part of which are 

 only known in the fossil state. The animal seems to inhabit the depths of the sea. 

 The fossil species are found in England in limestone, carboniferous limestone, oolite, 

 chalk, and green sand. 



* Shell smooth^ without longitudinal striae or furrows. 

 T. vitrea, Lam. (Anomia, Gmel.) Shell ovate, ventricose, hyaline, 

 thin, smooth, truncated in front, with one summit perforated and 

 inflected over the other. 16 lines long. Inhabits Mediterranean 

 and Northern seas D'Argenv. Zoom. pi. 12, fig. E. 



T. pisum, Lam. Shell small, subglobose, smooth, subantiquated ; 

 margin entire, and strongly sinuated before. Size of a cherry 

 stone. Inhabits Indian seas. Lam. vi. 1. 245. 



** Shell longitudinally furrowed. 



T. caput serpentis, Lam. (Anomia, Gmel.) Shell ovate, longitu- 

 dinally grooved, with the summit of the convex valve elevated and 

 perforated ; margin sinuous and crenulated. 1| inch long 

 Chem. viii. pi. 78, fig. 712. 



T. psittacea, Lam. (Anomia, Gmel.) Shell globose, gibbous, horny, 

 pellucid, and finely striated longitudinally ; umbo of the convex 

 valve much produced and perforated ; margin sinuated. 1| inch 

 long. Inhabits Northern seas. Brown's Illust. pi. 10*, fig. 2, 4. 



Gen. 3. ORBICULA, Lam. Patella, Mull. 

 Shell suborbicular, inequivalve, without apparent hinge ; low- 

 er valve very thin, flattened, adhering to marine bodies ; up- 

 per valve subconic, with the summit more or less elevated. 



O. Norwegica, Lam. Upper valve in the form of a depressed cone ; 

 summit pointed. Inhabits Northern seas Lam. vi. 2. 242. 



FAMILY II. RUDISTA. 



Ligament, hinge, and animal unknown ; shell with very un- 

 equal valves ; no distinct hooks. 



Gen. 4. CRANIA, Lam. Anomia, Gmel. 

 Shell inequivalve, suborbicular ; lower valve almost flat, and 



