132. MOLLUSCA FROM THE CRAG. 
Cyamium.* Philippi, 1845. 
Cyamium? Lovén, 1846. 
Turtonta? Hanley, 1849. 
Generic Character. Shell ovate, equivalve, inequilateral, closed, small, and thin: 
externally free from ornament. Hinge with two cardinal teeth. Palleal impression 
entire. Ligament internal. 
This genus has been proposed for a species found in the Antarctic Seas, with an 
internal ligament, and was adopted by Dr. Lovén for the little shell called Mya 
purpurea by Montague, which has however been erected into a genus by the Authors 
of the ‘ Hist. of Brit. Moll.’ under the name of Zurtonia, in consequence of its having 
an external ligament. 
CyaMIuUM? ExIMIUM, S. Wood. Tab. XI, fig. 5, a, 6. 
Spec. Char. Testé minima, ovatd, transversd, inequilaterali, levigatd, tenui ; posticé 
longiore, utrinque rotundatd ; cardine bidentato, uno laterali remoto pone ligamentum ; 
apicibus prominentibus. 
Shell small, ovate, transverse, inequilateral, smooth and thin; posterior side the 
larger, both sides rounded. Hinge with two cardinal teeth, and one remote lateral 
tooth behind the ligament; umbones prominent. 
Length, +th. Height, +;th of an inch. 
Locality. Coralline Crag, Sutton. 
One specimen of a species that appears to possess characters most in accordance 
with the diagnosis of this Genus, is in my Cabinet, and I am induced to place it 
here provisionally until some more shall be found, either to establish its right to 
the position, or to remove it; the desire that everything found in the Crag should 
be brought under notice must be advanced as an apology for the introduction of some 
few imperfect materials here, as well as elsewhere, in this Monograph. 
Our shell has an undoubted right to be specifically removed from Jdya purpurea, 
Mont., though in some of its characters there is a resemblance. The specimen 
figured is the left valve ; it has two distinct, rather prominent, soft teeth close to the 
umbo on the anterior side of the ligament, one standing at right angles to the length 
of the shell, and the other, a larger one, diverging towards the anterior side, with 
a sufficient space between them for the imsertion of a tooth which the opposite valve is 
supposed to possess: behind these teeth is a depression, where it is presumed the 
ligament was placed, and if it were so, it must have been wholly internal, and invisible 
* Etym. Kuadmuoy, a little bean. 
