121 



Placuiianomia foliata, Broderip, Proc. Zool. Soc. 1834, 2. 



P. echinata, Broderip, Proc. Zool. Soc. 1834, 2. 



" P. pectinata, Brod." in Mus. Cuming. 



Hab. Eastern Columbia, Bay of Guayaquil. Isle of Muerte ; Bro- 

 derip. Martinique, n. 6, and Brazils, n. 7 ; Mus. Cuming. Jamaica 

 (upper valve of young only) ; Rev. L. Guilding ; Brit. Mus. 



The specimen of Placunanomia echinata, from the island of Nevis, 

 in INIr. Cuming's collection, appears to be only an imperfect specimen 

 of this species. Mr. Broderip doubted if this might not be the case, 

 when he described it. 



4. Placunanomia abnormalis. 

 White, radiated, ribbed. 



Upper valve with two scars, confluent on the lower hinder edge ; 

 the upper one rather the largest. y>- 



" Placunomia abnormalis. Sow." in Brit. Mus. 



Hab. West Indies. 



These three species are very nearly related to each other, and if it 

 were not for the difference in the position of the scars, might be taken 

 for one. The first is white, and the two last have a brown blotch 

 on the internal surface of the dorsal valve. 



*** Shell ovate, not plicated ; radiately ribbed. Perforation of 

 lower valve large, only slightly embracing the large thin plug. 



MONIA. 



5. Placunanomia macrochisma. 



Upper valve with two scars, partly confluent on the lower hinder 

 edge ; the upper scar largest. Lower valve with an oval oblique scar, 

 narrowed behind, rather in front of the plug. 



Anomia macrochisma, Deshayes, Rev. Soc. Cuvier. 1839, 359 ; 

 Mag. de Zool. 1841, t. 34. 



Placunanomia Broderipii, Gray, B. M. 1842, and Mus. Cuming. 



Hab. Kamtschatka ; Deshayes. " Onalaski," Mus. Cuming. " Ca- 

 gayan, Lucon," fide " G. B. Sowerby," in Brit. Mus. 



M. Deshayes observes : " On salt que dans le plus grand nombre 

 des Anomies la perforation se reduit ordinairement en un simple 

 e'chancrure, parce que les deux parties du bord supcrieur ne se rejoi- 

 gnent jamais. Ici au contraire le trou est complete, et la valve est 

 reellement perforce." This character is common to all the species of 

 Placunanomia. M. Deshayes does not figure nor describe the plug. 

 I think the habitat assigned to this species by Mr. G. B. Sowerby 

 must be a mistake. It is the specimen referred to by Mr. Broderip 

 in the observations on the genus in the Proceedings of the Zoological 

 Society. 



6. Placunanomia cepio. 



Scars 2, far apart ; upper very large, ovate, longitudinal, central ; S 1^ 

 lower smaller, oblong, oblique, rather behind the upper. 

 Plug large, flat, broad. Notch large, wide. 

 Hab. California ; Lady Katherine Wigram ; Brit. Mus. 



