CONCHIFERA. 499 
Fossil ? Miocene—. Europe. (100 species. Lower Silurian— 
D’Orbigny. ) 
? Entodesma (Chilensis), Phil. Shell thin, saxicaya-shaped, 
slightly inequivalye and gaping, covered with thick epidermis ; 
hinge edentulous; each valve with a semicircular process con- 
taining the cartilage. 
PANDORA (Solander), Bruguiére. 
Type, P. rostrata, Pl. XXII., Fig. 11. (Pandora, the Grecian 
Eve. 
oe inequiyalye, thin, pearly inside; valves close, attenuated 
behind; right valve flat, with a diverging ridge and cartilage 
furrows; left valve convex, with two diverging grooves at the 
hinge; pallial line slightly sinuated. Outer layer of regular, 
_ vertical, prismatic cells, 250 times smaller than those of Pinna 
(Fig. 217). (Carpenter. ) 
Animal with mantle closed, except a small opening for the 
narrow, tongue-shaped foot; siphons very short, united nearly 
throughout, ends diverging, ‘fringed ; palpi Fonaculen. narrow ; 
gills plaited, one on each side, with a narrow dorsal border. 
Distribution, 18 species. United States, Spitzbergen, Jersey, 
Canaries, India, New Zealand, Panama; 4—110 fathoms, bur- 
rowing in sand and mud. 
Fossil, 14 species. Carb.—. United States, Britain. 
Myapora, Gray. 
Type, M. brevis, Pl. XXITI., Fig. 12. 
Shell trigonal, rounded in front, attenuated and truncated 
behind ; right valve convex, left flat; interior pearly ; cartilage 
narrow, triangular, between two tooth-lke ridges in the left 
valve, with a free sickle-shaped ossicle; pallial line sinuated ; 
structure like Anatina ; outer cells large, rather prismatic. 
Distribution, 10 species. New Zealand, New South Wales, 
Philippines. 
Myocuama, Stutchbury. 
-Type, M. anomioides, Pl. X XIII., Fig. 13. 
Shell inequivalve, attached by the dextral va.ve and modified 
by form of surface of attachment; posterior side attenuated ; 
left valve gibbose; cartilage internal, between two tooth-like 
projections in each valve, and furnished with a movable ossicle; 
anterior muscular impression curved, posterior rounded, pallial 
sinus small. 
Animal with mantle-lobes united; pedal opening and siphon : 
