78 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 



ASTARTE HILPERTENSIS, Lt/c. Tab. XXXVI, fig. 10. 



Testa crassa, convexa, ovato-trigonata, umbonibus subanticis prominentibus, lunula ovata 

 profunda, margine cardinali curvato, elongate, oblique declivi, marginibus anterioribus, pos- 

 terioribus et inferioribus ellipticis curvatis ; superficie plicis incrementi crebris tenuibus. 



Shell thick, convex, ovately trigonal ; umbones antero-mesial, elevated, and curved 

 forwards; lunule smooth, ovate, deep ; hinge-margin lengthened, curved, sloping obliquely 

 downwards ; the anterior, posterior, and lower borders curved elliptically ; the surface with 

 delicate, numerous plications of growth. 



A large, thick species, somewhat allied to A. subtrigona, Murist., but more convex, less 

 angulated, and with a larger lunule. 



Geological Position and Locality. The Cornbrash of Hilperton, Wilts, in the collection 

 of W. Walton, Esq. 



ASTARTE AYTONKNSIS, Bean MSS. Tab. XL, fig. 13. 



Testa ovato-oblonga, valde elongata, compressa, umbonibus depressis antemedianis, 

 lunula concava, margine cardinali subhorizontali elongata, margine inferiore parallelo ; latc- 

 ribus ruffis ellipticis, crebris, depressis subregularibus instructis. 



Shell ovately oblong, much elongated, compressed; umbones anterior to the middle of 

 the valves flattened ; lunule concave ; the hinge-margin lengthened and nearly horizontal ; 

 lower border conformable; the two extremities elliptically rounded ; the surface with closely 

 arranged, depressed, rounded, elliptical, partially irregular rugae. 



The general aspect has some resemblance to the shell figured in Part II, PI. IX, figs. 

 18, 19, as a variety of Astarte excavata, but still more flattened and more elongated, with 

 more conspicuous, regular, elliptical ruga3. Additional experience now leads me to rank A. 

 excavata, var. compressiuscula, as a distinct species, and not as a dwarfed variety of the large 

 Inferior Oolite shell ; the present form is even more thin and flattened than compressiuscula, 

 so much so as scarcely to allow any space for the animal. 



Length nearly twice the height ; the diameter through the united valves is little more 

 than equivalent to their apparent thickness. 



Geological Positions and Localities. The Great Oolite of Hampton Cliffs and of 

 Comb Down, near Bath ; collected by W. Walton, Esq. It occurs also in the Calcareous 

 Grit of Ayton, near Scarborough, quite unaltered in any particular ; the name from the 

 locality having been adopted by Mr. Bean many years since, and sent to public collections, 

 has therefore been retained. 



