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. Calyptrcea. A conoidal and spiral univalve; the 

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

 process proceeding from the internal summit, Recent 

 and fossil. PL iii. fig. 13. 



14. Infundibulum. 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. 



I have adopted Mr. Sowerb^'s description of this genus, 

 agreeing with that gentleman in the propriety of separating 

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

 Denys de Montfort. 



1 5. Crepidula. An oblong, vaulted univalve ; the apex 

 inclined to the edge ; the cavity partially divided by a 

 simple .diaphragm. Recent, and very rarely fossil. 

 PL iii. fig. 15. 



16. Dentalium. A tubular, tapering, slightly bowed 

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

 PL 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 sedentaires of Lamarck. 



