158 



12. Haliotis. — An oval, flattish, and ear-formed univalve, 

 with a depressed spire and row of round holes along the right 

 edge ; the opening large, and longer than wide. Recent. — 

 PI. iii. fig. 12. 



13. Calyptr(Ba.-—K conoidal and spiral univalve ; the 

 apex entire, and rather depressed ; with a folded tongue-like 

 process proceeding from the internal summit- Recent 

 and fossil. — PI. iii. fig. 13. 



14. Infundihulum. — A conical univalve ; hollow beneath, 

 spirally twisted, with a central spiral columella, and a spi- 

 rally decurrent plate or valve within ; mouth round, ex- 

 panded ; lip entire and sharp. Recent and fossil. — PL iii. 

 fig. 14. 



1 have adopted Mr. Sovverby's description of this genus, 

 agreeing with that gentleman in the propriety of separating 

 this shell from the genus calyptrcBai as has been done by M. 

 Denys de Montfort. 



15. Crepidula. — An oblong, vaulted univalve; the apex 

 inclined to the edge ; the cavity partially divided by a 

 simple diaphragm. Recent, and very rarely fossil. — 

 PI. iii. fig. 15. 



16. Dentalium. — A tubular, tapering, slightly bowed 

 univalve ; open at both ends.* Recent and fossil. — 

 PI. iii. fig. 16. 



17. Siliquaria. — A tubular univalve, spiral at the be- 

 ginning, and continued in an irregular tubular form ; par- 

 tially divided at the side by a narrow sharply dentated slit, 

 and sometimes formed into chambers by partial septa. 

 Fossil.— PL iii. fig. 17. 



The commencing spiral turn is omitted in the figure, to 

 give a better opportunity of showing the peculiar charac- 

 teristic of the shell, its dentelated fissure. 



* Dentalium, siliquaria, vermicularia, and serpula, belong to les 

 annelides sedent aires of Lamarck. 



