240 MOLLUSCA FROM THE CRAG. 
4. Apra oBpovalts, S. Wood. Tab. XXU, fig. 11. 
AMPHIDESMA OBOVALE. S. Wood. Catalogue, 1840. 
Erycina ovata? Phil. En. Moll. Sic., vol. i, p. 13, t. 1, fig. 13, 1836. 
TELLINA RUBIGINOSA? Poli. Vol.i, p. 48, t. 15, fig. 31, 1791, sec. Phil. 
Spec. Char. Testd ovatd, crassiusculd, subequilaterali ; anticé rotundatd, conver d ; 
postice angulatd, compressiusculd ; dentibus lateralibus magnis, elevatis, approximatis ; 
apicibus prominulis ; impressione palliart magno profundo. 
Shell ovate, rather thick, nearly equilateral, smooth; anterior side rounded, some- 
what tumid; posterior angulated, and slightly compressed ; lateral hinge teeth large, 
elevated, and proximate; apicesrather prominent ; palleal impression large and deep. 
Length, 4 inch nearly. Height, = inch. 
Locality. Red Crag, Sutton. 
Mam. Crag, near Norwich. 
Only two specimens of this species have come under my observation ; one was from 
the Mam. Crag, given to me by Mr. Charlesworth, the other I found in the Red Crag at 
Sutton: they are both unfortunately the right valve. Perhaps the shell described by 
Philippi above referred to is the same species, but the figure is by no means good, and 
the description does not altogether accord with the Crag shell, which is thick, and not 
thin, as therein described ; our shell has a remarkably thick hinge and a large, angular, 
or spoon-shaped area for the cartilage, behind which are two small cardinal teeth, and 
at a little distance are two prominent angular denticles; the posterior one close to the 
extremity of the hinge pit; the palleal sinus is very large, extending into the shell more 
than two thirds of its entire length. It differs from 4. /enuis in being more pointed, 
and it has a more strongly marked hinge. 
A shell much resembling this species has been obtained on the N. E. Coast of 
America, called Cummingia tellinoides, Conrad, 1830, Gould, ‘ Invert. Massach.,’ p. 56, 
fig. 36, and Stumpson ‘ Catal.,’ p. 20, but it is specifically distinct. The Crag shell is 
not so much compressed; the ventral margin is more convex, and the lateral teeth of 
the hinge larger and more prominent; while the American shell is also different 
externally, being covered with larger and more regular ridges. 
EPrycina ovata, Midden, t. 19, figs. 5—8, as well as Amphidesma ovata, Desh. ‘ Expéd. 
Morée,’ pl. 6, fig. 8, appear, from the figures and descriptions, to be different from our 
shell. 
Mactra,* Linneus, 1767. 
CaALLIsTA CaLLIsTODERMA (sp.) Poli, 1791. Spisuta. Gray, 1837; 1851. 
TRIGONELLA (sp.) Da Costa, 1778. | MesopmsMa (sp.) Desh. 1835. 
Muuinia. Gray, 1836. | Hemimactra. Swains. 1840. 
* Etym. paxrpa, a kneading trough. 
