270 MOLLUSCA FROM THE CRAG. 
Carpenter, that gentleman seems to think it so peculiar, as almost to constitute a 
family by itself. He describes the exterior as composed of regular prismatic cells, 
the axes of the prisms being perpendicular to the surface, while the interior is 
nacreous. 
No well-determined species have been met with in the fossil state in any Formation 
older than the Paris Basin. A shell from the Carboniferous Series is described by 
Professor M‘Coy under this name; but its claim to a place in this genus is very 
doubtful. 
1. PANDORA INZQUIVALVIS, Linn. Tab. XXV, fig. 5. 
TELLINA INMQUIVALVIS. Linn. Syst. Nat., ed. 12, p. 1118, No. 56, 1767. 
— — Poli. Test. utri. Sicil., vol. i, p 39, pl. 15, figs. 5, 6, 9, and 7 
with the animal. 
— — Don. Brit. Shells, vol. ii, pl. 41, fig. 1, 1800. 
PANDORA ROSTRATA. Desh, 2d ed. Lamarck, tom. vi, p. 145. 
os — G. B. Sowerby. Spec. Conch. Pandora, p. 2, No. 2, figs. 7—9. 
— — Phil. En. Moll. Sic., vol. i, pl. 1, fig. 12, 1836. 
— — Desh. Exp. Scient. Algér. Moll., pl. 24, animal. 
= — ‘orb. and Hanl. Hist. Brit. Moll., vol. i, p. 207, pl. 8, figs. 1—4. 
—  MARGARITACEA. Lamk. Hist. des An.s. Vert., tom. v, p. 137. 
— — Schum. Essai des Vers. Test., p. 114, pl. 4, fig. 2. 
— — Turt. Brit. Biv., p. 40, pl. 3, figs. 11—14, 1822. 
— una#quivatvis. Flem. Brit. Anim., p. 466, 1828. 
Spec. Char. Testa elongato-ovata, levigatd, tenui fragili, inequilaterali ; latere postico 
longiore, attenuato subrostrato, hinc in utraque valvd angulato. 
Shell elongately ovate, smooth, thin and fragile, inequilateral ; posterior side the 
longer, attenuated, and somewhat beaked, slightly angulated in each valve. 
Length, = inch. Height, = inch. 
Locality. Cor. Crag, Sutton. Recent, Britain and Mediterranean. 
My specimens of this species are but few, and those not in good condition. The 
one figured has the siphonal area elongated into the form of a rostrum or beak, and 
corresponds with what the British conchologists have considered a distinct species. 
In the young state, as indicated by the lines of growth, the dorsal margin is more 
convex than concave, and the shell comparatively broader, like P. Pinna, and there is 
no appearance then of a rostrum. 
2. PANDORA PinNA, Montague. Tab. XXV, fig. 4, a—c. 
Soten Pinna. Mont. Test. Brit., p. 566, t. 15, fig. 3, 1803. 
Panpora optusa. Leach. Ross’s Voy. Baffin’s Bay, p. 174, 1819. 
