ELECTRINA. MEGALOMASTOMA. REGISTOMA. 31 



Meg. tortuosum Pfeiffer, 1. c. 102. n. 3. 



a. Nicobar Islands. From the Collection of Lord Tankerville. 



2. Megalomastoma altum. 



Cyclost altum Sow. Thes. Conch, i. 152. n. 173. t. 28. f. 187.; 



Pfeiffer, Kuster, Chemn. Conch. Cab. i. 19. t. 15. f. 12—14. 

 Cyclost. brunneum Gould? 

 Meg. altum Pfeiffer, 1. c. 109. n. 1. 



a — c. Isle of Negros. From the Collection of Mr. Cuming. 



3. Megalomastoma funiculatum. 



Cyclostoma funiculatum Benson MS. 



a — c. Darjeeling. From the Collection of Capt. Boys. 

 d, e. Himalaya. Presented by Dr. Horsfield. 



4. Megalomastoma Layardii. 



a. Ceylon. Presented by H. L. Layard, Esq. 



§§ Peristome not thickened near the penultimate whorl. America. 



5. Megalomastoma Antillarum. 



Cyclost. Antillarum Sow. Thes. Conch, i. 150. n. 168. t. 28. f. 180.; 



Pfeiffer, Kuster, Chemn. Conch. Cab. i. 19. t. 15. f. 15, 16. 

 Cyclost. elongatum Gould MS. 

 Megalomastoma elongatum Swainson, Malac. 1840. 

 Cyclost. suspensum Guild. 



Megalomastoma suspensum Pfeiff. 1. c. 109. n. 11. 

 Meg. Antillarum Pfeiff. 1. c. 109. n. 2. 



a—n. St. Vincent's, W. Indies. From the Collection of Key. 



Lansdown Guilding. 

 o— q. ? 



12. REGISTOMA. 



Shell oval, polished. Whorls rather distorted, large, flattened. 

 Mouth orbicular. Peristome reflexed, inner lip thin, with a 

 slight notch on the inner side near the axis. 



Registoma Hasselt, Allg. Konst. en Letterbode, 1823 ; Ferussac, 

 Bulletin Sci. 1824; Gray, Syn. B.M. 1842, 91., Proc. Zool 

 Soc. 1847, 182. 



Rhegostoma Agassiz, Nomenclat. Zoolog. 



Rhexistoma Hermannsen, Ind. Gen. ii. 390. 



b 4 



