30 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 
BIVALVIA. 
Grypnza minvta, Sow. Tab. XL, fig. 30. ¥ 
GRYPH#HA MINUTA, Sowerby. Min. Con., tab. 547, fig. 4. 
—— — Morris. Catal. Brit. Foss., p. 186. 
Testa parva, valva majora suborbiculata, umboni incurvo, lateré anticd suled brevi 
instruct6. Valva altera ignota. / 
Shell small; the larger valve subglobose, suborbicular ; the beak produced, incurved, 
and nearly straight, only slightly roughened by the area of attachment; the anterior side 
with a short sulcation, but no distinct lateral lobe. The smaller valve is unknown. 
A minute Grypheea, of which several specimens have been obtained by Mr. Witchell 
in the Minchinhampton Great Oolite; it has no well-defined distinctive features, and 
would scarcely have been deemed worthy of notice had it not been figured by Mr. Sowerby. 
from Ancliff. 
PLACUNOPSIS SEMISTRIATUS, Bean, sp. Tab. XXXIII, figs. 9, 9 a. 
ANOMIA SEMISTRIATA, Bean. Mag. Nat. Hist., 1839, p. 61, fig. 21. 
Testa, valva majora convexa, subobliqua, ovato rotundata, apice submarginali, acuta, 
lamellis concentricis, irregularibis, superne levigata, inferne lineis radiantibus subequalibus 
nodulosis ornata. Valva afixa wgnota. 
Shell with the larger valve ovate, slightly oblique, convex; the apex pointed, and 
placed near to the margin; the surface has numerous irregular, concentric lamelle ; the 
lower portion has numerous radiating lines, which are nearly equal, granulated, and 
undulated. The attached valve has not been obtained. 
The test appears to be less delicate than is found in some other examples of the genus, 
and is usually affixed to another shell, more especially to Zerebratula lagenalis, so that it 
is scarcely possible to obtain a specimen whose figure has not been affected by some 
extraneous body. The general aspect has much resemblance to P/acunopsis Jurensis 
((Gr. Ool. Monog. Biv.,’ tab. i, fig. 13), but the latter has the ornamentation of the 
surface much more strongly defined, with larger and more densely arranged radiating lines. 
In P. semistriatus these can only be discerned with a magnifier. 
Geological Position and Locality. The Cornbrash of the Yorkshire Coast, at Gris- 
thorpe and Scarborough, where it is moderately rare. The upper portion of the 
Inferior Oolite in the Cotteswold Hills has a species probably identical with this Pla- 
cunopsis, and possessing a similar kind of ornamentation. 
