ANOMIAD^. 
11 
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 ovale, not plicated ; radiately ribbed. Perforation of 
lower valve large, only slightly embracing the large thin plug. 
Monia. 
Monia, Gray, P. Z. S. 1849, 121. 
f American. 
5. Placunanomia macbochisjia. 
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. Cuvier, Zool. 1839, 369; 
Mag. de Zool. 1841, t. 34. 
Placunanomia Broderipii, Gray, B. M. 1842, and Mus. Cuming. 
Placunanomia macrochisma, Gray, P. Z. S. 1849, 121. 
a, b. Kamtschatka. 
M. Deshayes observes ; “ On sait que dans le plus grand nombre 
des Anomies la perforation se reduit ordinairement en un simple 
echancrure, parce que les deux parties du bord superieur ne se re- 
joignent jamais. Ici au contraire le troa est complete, et la valve 
est reellement perforee.’’ This character is common to all the spe- 
cies of Placunanomia. M. Deshayes does not figure nor describe 
the plug. The habitat, “Cagayan, Lucon,’’ assigned to this species 
by Mr. G. B. Sowerby must be a mistake. It is the specimen refer- 
red to by Mr. Broderip in the observations on the genus in the Pro- 
ceedings of the Zoological Society. 
6. Placunanomia cepio. 
Scars two, far apart ; upper very large, ovate, longitudinal, cen- 
tral ; lower smaller, oblong, oblique, rather behind the upper. 
Plug large, flat, broad. Notch large, wide. 
Placunanomia Cepio, Gray, P. Z. S. 1849, 121. 
a. Adult, California. Presented by Lady Katherine Wigram. 
