BIVALVIA. 75 
concentricis, regularibus, angustis, elevatis (16—18) striisque subtillissimis, concentricis, 
impressis. 
Shell small, suborbicular, much inflated ; umbones large, mesial, incurved ; posterior and 
lower margins rounded ; lunule very large, concave, its margins rounded ; the surfaces of 
the valves have narrow, concentric, regular, elevated costee, 16—18 in number, which are 
impressed by very delicate concentric striations ; the intercostal spaces are upwards of three 
or four times the breadth of the costa. 
Height, lateral diameter, and diameter through both the valves, each about 4 lines. 
About thrice the size of a minute Cotteswold Inferior Oolite species which possesses 
a similar figure, but whose costa are irregular. Astarte Bulla, Goldf., is also globose, but 
has only half the number of costa. 4. integra, Goldf., has less convexity and is more 
oblique ; other small species, figured by Roemer, Buvignier, and by Quenstedt, have less 
convexity and more obliquity. 
Geological Position and Locality. One of the more rare testacea of the Scarborough 
Cornbrash; in the collection of Mr. Leckenby. 
AstartE Pontonis, Lyc. Tab. XU, fig. 31. 
Testa parva, convexa, ovato-orbiculari, umbonibus submedianis, acuminatis, antrorsum 
curvatis, margine cardinali elongato, subrecto, oblique declivi, lunula magna, costata ; valvis 
costis concentricis numerosis (20) elevatis, rotundis, interstis angustis ; latere superiore, 
area, elongata, planata et levigata. 
Shell small, convex, ovately orbicular; umbones elevated, pointed, nearly mesial, and 
curved forwards ; hinge-border lengthened, nearly straight, slopmg obliquely downwards, 
forming a narrow, smooth area, separated from the costated part of the shell by an acute 
angle; the lunule is large, costated, and somewhat excavated ; the surfaces of the valves 
have large, numerous (about 20) concentric, elevated, and rounded costa, separated 
by more narrow interstitial spaces; adult shells have a large fold of growth near to the 
lower border. 
A small, convex, neatly ornamented species, allied to 4. minima, Phil., and A. pisum, 
Kock and Dunker ; from the former it is distinguished by the more numerous and more 
closely arranged costs, by the more pointed and more curved umbones, by the larger 
lunule, and by the posterior, straight, smooth, acutely bordered area; the latter feature will 
also separate it from A. piswm and from A. supracorallina, D’Orb. 
The height and lateral diameter are about 4 lines. 
Geological Position and Localities. It is abundant in the White Oolite (Great 
Oolite ?) of Ponton, Lincolnshire. 
