72 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 
shorter, more convex, the test thicker, the umbones larger, less oblique, and more obtuse ; 
the posterior flattened area is also a distinguishing feature when it is present. 
Geological Position and Localities. The Forest Marble of Laycock and Farleigh, in 
the collection of W. Walton, Esq., of Bath. 
ASTARTE UNGULATA, PAtl., sp. Tab. XXXV, fig. 20. 
ASTARTE LuRIDA, Phil. Geol. York., i, pl. 5, fig. 2, p. 137, non A. lurida, Sow. 
— — Williamson. Trans. Geol. Soc., 2d ser., vol. vi, p. 149. 
— — Bean, on Cornbrash Fossils, Mag. Nat. Hist., 1839. 
a —  Leckenby, on Kelloway Rock Fossils, Journ, Geol. Soc., 1858. 
Testa suborbiculari aut subquadrangulari, depressa, inequilatera, ad peripheriam con- 
centrice costellata, costellis elevatis, subangularibus, concentrice subtillissime striatis ; 
costellis inferne evanescentibus ; margine cardinali curvato, lunula subnulla. 
Shell suborbicular or somewhat subquadrangular, depressed, inequilateral ; umbones 
small and only slightly produced; posterior and inferior margins rounded, lunule, 
ebsolete ; the surface near to the umbo with elevated acute concentric rugs, which are 
impressed with very delicate concentric striations ; the rug disappear towards the middle 
of the valve, the lower portion having only some plications of growth. 
The character of the surface has a considerable resemblance to Astarte Wiltoni, ‘ Gr. 
Ool. Monogr.,’ Tab. IX, f. 16 ; but the latter has the umbo much more produced, it has a 
distinctly excavated lunule and is more convex ; other depressed species are sufficiently 
separated by their ornamentation. 
Astarte lurida, Sow., which occurs in Gloucestershire at Nailsworth in gray shale 
near to the upper boundary of the Upper Lias, and in the lower portion of the overlying 
Supraliassic Sands associated with Ammonites variabilis, is a very different shell, whose 
figure is ovately trigonal and moderately convex, with prominent apex, well-marked lunule 
and depressed concentric rugz ; it does not therefore present a near approximation to our 
species. 
Astarte ungulata has the height and lateral diameter equal ; the valves are moderately 
thick ; the size varies from 4 to 10 lines across. It is rare. 
Geological Positions and Localities. Professor Phillips figured the interior of a valve 
from the Oxford Clay of Scarborough. Mr. Leckenby has recorded it in the Kelloway 
Rock of the same locality; our figure is taken from a Cornbrash specimen of the same 
coast now in the collection of Mr. Leckenby, and formerly in that of Mr. Bean, who 
identified the species with that originally figured in the ‘ Geology of Yorkshire.’ 
