406 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Mar. 23,
faint lines of growth ; aperture oval; subtruncated in front ; outer
lip thin ; columella without a fold.
Length 0.27 inch ; last whorl about 6/10 the length of the shell.
Locality. Yellow Lias (zone of Am. ibex) Hewletts, Cheltenham.
Cerithium: Slatteri, nov. sp. (Pl. XXVI. fig. 7.)
Shell elongated, turreted, acute; whorls ten, subquadrate, separated by a broad and deep suture; ornamented by about twenty-five obliquely transverse ribs, which, where crossed by the four equidistant longitudinal costae, are raised into large closely set nodulations ; aperture orbicular ; columella straight, outer lip slightly effuse.
The longitudinal ribs are sometimes three in number, and not unfrequently with a smaller intermediate rib.
Length 0.25 inch.
Locality. Zone of Am. Jamesoni: Aston (T.S.), Cheltenham (R. T.).
The species is dedicated to T. Slatter, Esq., whose collection of fossils from Aston Magna has materially increased the value of the present communication.
Lima scabricula, nov. sp. (Pl. XXVI. fig. 15.)
Shell convex, oblong-ovate, ornamented with about twelve large acute costae, which are finely and closely transversely striated, and towards the front carry nodes; the sulci are occupied by three slender costellae, the outer ones of which are crenately dentate ; the median costella is lamelliform ; hinge-line straight, beaks acute and distant ; hinge-area narrow, elongated ; ligamental pit circular, external ; ears short with radiating nodulose ribs.
Dimensions. Length 0.515 inch ; breadth 0.4 inch ; thickness 0.35 inch ; length of hinge-line 0.22 inch.
Affinities. L. scabricula has much the figure of some varieties of Limea acuticosta, Lima hettangensis, L. pectinoides, &c, but differs from all in combining the characteristic ornamentation of several of the duplicate Limoe, none of which, however, present the intermediate ribs as in this species.
Locality. Zone of Ammonites Jamesoni : Aston Magna (Slatter) ; Middle Lias (Am. margaritatus), Fontaine-etoupe-four, Caen (Tesson, Coll. Brit. Mus.)
Arca numismalis, nov. sp. (Pl. XXVI. fig. 3.)
Shell small, oblong, inflated, inequilateral; anterior side short, subtruncate, posterior obliquely truncate; umbones large, sub-approximate, incurved and directed forwards, medially impressed ; surface with undulate concentric ribs, which are subacute and minutely granulated ; apical portion of left valve with radiating costellae, of the right with fine striations.
Dimensions. Length 0.315 inch ; height 0.25 inch; diameter 0.2 inch ; length of anterior side 0.13 in.
Locality. Zone of Ammonites Jamesoni, Aston Magna (Slatter).
Anatina numismalis, nov. sp. (Pl. XXVI. fig. 13.)
Shell small, elliptic -elongate, subequilateral, and somewhat com-
