30 LIST OF CYCLOPHORIDJE. 



t. 31. f. 277.; Pfeiffer, Kuster, Chemn. Conch. Cab. i. 19. t. 17. 

 f. 12—17. 

 Megalomast. auriculatum Pfeiffer, 1. c. 109. n. 8. 



g. Cuba. Presented by E. Doubleday, Esq. 



Var. 3. 



Cyclost. alutaceum Menke, Pfeiffer, Kuster, Chemn. Conch. Cab. 



i. 19. t. 17. f. 18, 19. 

 Megalomast. alutaceum Pfeiffer, 1. c. 109. n, 9. 



Hab. ? 



10. ELECTRINA. 



Operculum orbicular, many-whorled, horny ? — Shell conical short, 

 covered with a thin periostraca. Spire conical. Axis perforated. 

 Whorls with a strongly marked keel in the front, forming an 

 edge to the axis. Mouth circular, continued, simple. 



Electrina Gray MS. B. M. 



1. Electrina succinea. 



Cyclost. succineum Sow. Zool. Proc. 1832, 32., Thes. Conch, i. 

 108. n. 51. t. 23. f. 18, 19. ; Milller, Synops. 37. ; Pfeiffer, Kuster 

 Chemn. Conch. Cab. 24. n. 15. i. 19 t. 3. f. 12. 13. magn. f. 14. 



Cyclost. australe Milhlf. Anton. Verz. 54. 



Cycloph. succineus Pfeiffer, 1. c. 108. n. 22. 



a— d. Opara. From the Collection of Mr. Cuming. 



11. MEGALOMASTOMA. 



Operculum horny, thin, closely whorled, flat. — Shell scarcely per- 

 forated, cylindrical or pupa-shaped, covered with a thin perios- 

 traca. Mouth orbicular, with a slight groove on front angle. 

 Peristome continuous, thickened or reflexed. Last whorl with 

 a ridge round the axis in front. 



Megalomastoma Gould MS. in Swains. Malac. 1840 ; Gray, Syn. 

 B.M. 1842, 91., Proc. Zool. Soc. 1847, 182.; Pfeiffer in Menke 

 und Pfeiffer, Z. f Malak. 1847. 



§ Peristome continued, thickened all round. Asia. 



1. Megalomastoma tortuosum. 



Turbo tortuosus Chemn. Conch. Cab. xi. t. 195. a. f. 1882. 1883. 

 Cyclost. tortuosum Sow. Thes. Conch, i. 152. n. 172. t. 28. f. 185, 

 186.; Pfeiffer, Kuster, Chemn. Conch. Cab. i. 19. t. 24. f. 19, 20. 



