274 WORMS, TESTACEA. 66. Oftrea. 
Anatinae Shell pellucid, lamellate and laterally incurved. 
Spengler catal. raif. tab. 6. fig. 1, 2. 
Chemn. conch. 8. tab. 70, f. 658. tab. 71, f. 656. 
Inhabits Nicobar lflands: about an inch broad, and including 
the curvature 5 inches long: its fhape in fome manner refem- 
bles a duck when fitting : fhe//thin, brittle, varied with white 
and violet, 
Diluviana, Shell plaited on the outfide; the margin with erect acutan- 
gular teeth. 
Found in a foffile ftate in the calcareous mountains of Saveden, 
about the fize of a common oyfter; the margin with ere¢t 
ferratures formed as it were of the imbricate lamelle of the 
fhell, and tranfverfely ftriate: valves with pectinate plaits 
and acute wrinkles, 
Tabu. Shell ovate, obtufely plaited at the fides, parafitical. 
Barbut, tab. 9, fig. 2. Rumpf. Muf. tab. 47, A. 
Petiv. Amb, tab. 10, f. 1. Argenv. conch. t. 19. F. 
Klein Oftr. tab. 8. sig. 22.  Spengl. conch, tab. 1. H. 
Knorr Vergn. 1. tab. 23, fig. 2. 
Chemn. conch. 8. tab. 71. fig. 662—666, 
2: Schrat. litterat. 2. tab. V. fig. 5, 6. 
Inhabits the Indias Ocean, where it is frequently found adhering 
to Gorgoniz : fhell ftraw-coulour, pale tawny or violet, within 
filvery : Ainge with a triangular hollow: upper-valve turgid on 
the back towards the middle, wrinkled each fide and traní- 
verfely ribbed; /ower-walve le(s flatter and grooved in the 
middle, 
Orbicularis Shell orbicular, flat, with an entire crenate margin. 
Gualt. tefl. tab.104, G. Chemn, 8. tab. 74. fig. 680? 
Inhabits Shell with a very obtufe margin, about the fize 
of the end joint of the thumb, 
*Edulis, Shell nearly orbicular and rugged, with undulate imbricate 
fcales: one valve flat and very entire. 
Pennant Brit. Zool. iv. tab 62, lower figure, 
Lister An. Ang. tab. 4. fig. 26. 
Lister conch. tab. 202. sig. 36. t. 203, f. 37- 
Bonan, recr. 2. fig. 70. Muf, Kircb. 2. f. 68. 
Gualt. teft. tab. 102. A, B. — Argenv. Zoom t. 5, As 
Bajter op. fubf 2. tab. 8, fig. 1,2. 8, 9, 
Gínann. adr. 2. tab. 18. fig. 127. 
Knorr Verga. 3- tab. 24, fig. 2. t. 25. f. 2. 
C hemn. conch, 8. tab. 74. fig. 682. 
2, Adanf. Seneg. 1, tab. 14. figs 5- 
Lister, tab. 393, 194. — Klein oftr. tab. 8. f. 2. j 
etn, 
