BIVALVIA. 239 
3. ABRA PRISMATICA, Montague. Tab. XXII, fig. 13, a, 6. 
LIGULA PRISMATICA. Mont. Test. Brit. Supp., p. 23, pl. 26, fig. 3, 1808 
_ — Brown. Must. Conch., Gt. Brit., pl. 14, fig. 5, 182 
—_ — Forb. Rep. Agean. Invert., p. 181, 1843. 
- 
Te 
ABRA — “Leach.” Lamk, Hist. des An, s. Vert., tom. vy, p. 492, 1818. 
Mya = Turt. Conch. Dict., p. 103, 1819. 
SynDosMyA — Recluz. Rev. Cuv. Zool., p. 367, 1843. 
i — DLovén. Ind. Moll. Scand., p. 45. 
— _ For. and Hanl. Hist. Brit. Moll., vol. i, p. 321, pl. 17, fig. 15. 
TELLINA stricta. Broc. Conch. Foss. Subap., p. 515, t. 12, fig. 3, 1817. 
—  onactrormis. Nyst. Rech. Coq. Foss. d’Anv., p. 5, pl. 1, fig. 17, 1836. 
LIGULA — Id. Coq. Foss. de Belg., p. 92, pl. 4, fig. 9, 1843. 
AMPHIDESMA PRISMATICUM. Turt. Brit. Biy., pl. 5, fig. 3, 1822. 
ErycINa ANGULOSA. “Bronn.” Phil. En. Moll. Sic., vol. ii, p- 9, 1844. 
Spec. Char. Testa elongato-ovatd, inequilaterali, levigatd, tenui ; latere postico duplo 
breviore; subrostrato ; dentibus lateralibus elongatis. 
Shell elongately ovate, inequilateral, smooth, and very thin; posterior side half the 
length of the anterior, and pointed; lateral teeth elongated. 
Length, # inch. Height, 3 inch. 
Locality. Cor. Crag, Sutton. 
Clyde Beds. Recent, Augean, British, and Norwegian Seas. 
I have met with this shell only in the Cor. Crag, and there not very abundantly. 
If there be any difference between this and the existing form, it is that the 
fossil appears rather the more tumid of the two. The ligamental area is small, and 
there are two small lateral denticles or dorsal elevations in the left valve, rather 
remote from the umbo, with one cardinal tooth; and two lateral denticles, and 
two cardinal teeth in the right valve; palleal impression not visible. The siphonal 
side is somewhat pointed and slightly compressed, forming an obscure angle or 
ridge on that side from the umbo to the posterior extremity. This species in the 
living state is said to have a vertical range of 100 fathoms, with a wide geographical 
extension from Norway to the Aigean, and there appears very little doubt that the 
fossil called Hrycina angulosa, from the Upper Tertaries of Calabria, belongs to the same 
species. It is found also in the Belgian Crag of Anvers. Ligula fragilis, Bosquet, 
‘Bull. de l’Acad. Roy.,’ tom. xviii, pl. 11, p. 305, fig. 1, a—d, a shell from Klein 
Spauwen, strongly resembles our species, but it is, I believe with that author who has 
pointed out the differences between the Belgian shells, quite distinct. Aimphidesma 
subrefleca, Conrad, p. 37, pl. 19, fig. 6, if one might judge from the figure alone, may 
perhaps be united with 4. prismatica. 
