183 
MANCHORA. 
Gen. Char. An attached inequivalved bivalve, the 
attached valve having an opening in place of a 
beak, the other beaked and eared ; hinge with- 
out teeth. 
Although I expect there are but few shells with these 
characters, I think the attached valve of importance enough 
to separate them as a distinct Genus from Plagiostoma, 
which in other respects they closely resemble. This charac~ 
ter is the more remarkable, as it is united with an angular 
aperture at the back of the shell, seemingly formed for the 
passage of a ligament, by which the animal could fix itself 
to rocks, &c. as in Plagiostoma. The beak and parts around 
it are mostly very thin, the ears small, and the general 
contour of the shell oblique. 
DIANCHORA striata. 
TAB. LXXX.—Fig. 1. 
Spec. Char. Oblique, ovate-triangular, beak pro- 
minent, free valve obscurely ribbed. 
Ijength and breadth nearly equal, and the form would be 
ovate, were it not for the projecting beak, from which the 
free valve is gradually flattened to a sharp edge, and which 
