5 



22 Mauiitianu nobis, Concli. lUustr. f. 17- Sliell ovate 



white, concentrically grooved, nearly equilateral, anter- 

 iorly rounded, posteriorly acuminated; dorsal slope 

 nearly equal on both bides ; length 0.4, breadth 02 

 height 0.25. From the Mauritius, G. Humphrey. 



23 limatula 5ay, American Conchology t. 12. 



24 k«vis Say, Amer. Conch, t. 12. 



25 concentrica Say, Amer. Conch, t. 12. 



*** ELLIPTICjE. 



26 margaritacea La7}i. Sow. Gen. of Shells, f. 7- British. 



27 decussata Ho6w, Conch. Illustr. f. 18. Shell somewhat 



triangular, white, decussately striated ; anterior side 

 shorter, its slope rather elevated in the middle ; poste- 

 rior side much longer, oblique ; ventral margin rounded 

 its edge crenated ; length 0-85, breadth 4, height 0-6. 

 Brought from the Coast of Guinea, in 1788, G. 

 Humphrey. 



28 rugulosa nobis. Conch. Illustr. f. 19. Shell ovate 



triangular, with a greenish epidermis, covered with 

 rugulose striae ; angles obtuse ; anterior slope with a 

 central elevation ; posterior slope somewhat rounded ; 

 ventral margin very finely crenulated ; length 5, 

 breadth 0.25, height 0-4. 



29 nitida nobis. Conch, Illustr. f. 20. Shell ovate sub- 



triangular, smooth, shining, white, with an olive co- 

 loured epidermis ; posterior slope somewhat rounded, 

 anterior nearly straight, with a central elevation ; 

 length 0-5, breadth 0-25, height 0-4. Common on the 

 British Coast. 



30 obliqua Lam. Conch. Illustr. f. 21. Valparaiso, Mr. 



Cuming. 



31 tenuis 3IonL Test. Brit. Sup. p. 56. t. 29. f. 1. Scar- 



borough, Frith of Forth, &c. 



32 convexa nobis. Conch. Illustr. f. 22. Shell ovate, turgid, 



whitish, smooth; anterior side shorter, slightly acumi- 



