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MOLLUSCA FROM 'THE CRAG. 
“Animal oblong, mantle closed in front, except a plain-edged orifice for the 
passage of a lanceolate foot; siphons short, united, unequal, the branchial largest, 
both bearing a few long filiform cirrhi at their sides, extending beyond the orifices ; 
anal siphon with a very extensile membranous valve.”—Jordes and Hanley. 
1. Nr@ra suaosa, S. Wood. Tab. XXX, fig. 7, a, 4. 
CorsuLa ? sutcatTa. S§. Wood. Catalogue, 1840. 
Spec. Char. Testa parva, transversd, inequilaterali, equivalvi ? compressa, jugosa ; 
anticé rotundatd; postice subrostratd, et angulatd ; cardine unidentato. 
Shell small, transverse, inequilateral, equivalved ? compressed, ridged ; anterior side 
rounded ; posterior somewhat beaked, and angulated; hinge with one tooth. 
Length, } inch. Leight, 2; inch. 
Locality. Cor. Crag, Sutton. 
This shell is not rare in the Coralline Crag, but as yet I have met with it only in 
one locality, and never with the valves united. 
It much resembles the figure of one of the species from the Paris Basin, Corbula 
striarella, Desh., Coq. Foss. des Env. de Par., tom. i, p. 54, pl. 8, figs. 12—15, but 
differs in being less than half the size, as well as in other characters; and I believe it 
to be distinct, depending as I am obliged to do upon the figure and description above 
referred to. 
In our species the hinge of the right valve has one obtuse and somewhat oblique 
tooth on the anterior side of the umbo, with a depression between it and the dorsal 
edge, into which fits an elevated portion of the margin of the left valve, while on the 
siphonal side of this (left valve) is an elongated and elevated projection that mterlocks 
within the dorsal edge of the right valve; between these, and immediately beneath 
the umbo, is an oblique pit, where the lgament was situated, and entirely 
within the shell; so much so that I doubt whether any part of it could have been 
seen in the living animal when the valves were closed. The dorsal margin 
slopes at an angle of about 45°, and a truncated beak is formed by the siphons; 
the upper part being somewhat elevated producing an obtuse keel from the umbo upon 
the slope on that side. The exterior has from eight to ten rounded ridges, with 
depressions or sulci between them of about the same breadth; but upon the younger 
part of the shells these markings are obsolete, beg smooth, or nearly so, about the 
umbo. The shell is by no means thin, though the ridges are generally visible upon 
the interior. The adductor-mark on the siphonal side is of a triangular form, and 
deeply impressed, placed rather backward; and the sinus in the mantle-mark mode- 
rately deep. 
The provisional name given to it in my ‘Catalogue’ is obliged to be changed, in 
consequence of its having been used by Dr. Lovén for a very different species. 
