130 MOLLUSCA FROM THE CRAG. 
Monrtacuta FrEerRuGINEA. Thorpe. Brit. Mar. Conch., p. 52, fig. 16, 1844. . 
_ ovata. SS. Wood. Catalogue, 1840. 
—— TENELLA? Lovén. Ind. Moll. Scand., p. 43, 1846. 
TELLIMYA OVATA. Brown. Ilust. Brit. Conch., pl. 14, figs. 20, 21, 1827. 
— ELLIPTICA. Id. - - - pl. 14, figs. 17, 18, ,, 
_ GLABRA. Id, + - - 2ded.,p. 107, pl. 42, figs. 20, 21. 
— ovata. Smith. Mem. Wern. Soc., vol. viii, p. 41, 1838. 
ERYCINA FERRUGINOSA. MRecluz. Rey. Zool. Cuv., p. 332, 1844. 
Spec. Char. Testd transversd, ellipticd, convexd, tenut, levigata vel concentricé striata ; 
antice longiore, posticé subattenuatd ; margine dorsali et ventrali leviter arcuatis. 
Shell transverse, elliptical, convex, thin, smooth, or striated concentrically, 
anterior side the longer, posterior slightly attenuated, dorsal and ventral margins 
gently curved. 
Length, 4 an inch. Height, ¢ of an inch. 
Locality. Cor. Crag, Sutton. Recent, Britain and Scandinavia. 
This is not an abundant shell in my Cabinet, a few specimens however are 
sufficiently perfect to be fairly compared with the recent British shell, and I believe 
the differences are not more than may be considered as local variations. 
Our shell is very transverse, having a length about twice that of its height, 
the anterior side occupying about three fifths of the entire shell; the posterior 
side is rather more pointed than in the recent specimens I have compared with, 
but in Messrs. Forbes and Hanley’s description of the living species, it seems 
to have a considerable range in variation, occasionally resembling our own shell 
in that character, which appears to be its only difference: in perfect specimens 
the exterior is covered with regular concentric strize, and the hinge is formed of an 
internal ligament of an angular form, deeply inserted, and slopmg towards the pos- 
terior side; a portion of the ligament was probably seen externally, as a small sinus 
is formed in the umbo, through which it might have extruded, this pit, or support 
for the ligament is thickened at the edges, and elevated behind, so as to produce a 
sort of denticle in the left valve, and immediately before it is a distinct though not a 
prominent tooth, the same appearances are exhibited in the right valve, in which the 
tooth is rather more elevated. There are large adductor muscle marks of an ovate 
form, and the impression by the mantle is entire. 
The animal of this species has been recently examined by Mr. Alder, who has 
published his observations in the ‘Ann. and Mag. of Nat. Hist.’ for the present year, 
where he has pointed outa peculiarity in the mantle on the anterior side, by which it 
appears, he says, to connect the open-lobed form in Zepfox with the anterior tubular 
extension of that organ in Kellia. 
Very extraordinary forms are assumed by the fleshy covering or mantle in many 
of the animals of this group, presenting us with distinctions so apparently anomalous 
as to entitle them, if distinguished by that organ alone, to be removed to very distant 
