76 SUPPLEMENT TO GREAT OOLITE MOLLUSCA. 



AsTARTE Bathonica, Lyc. Tab. XL, figs. 23, 23 a. 



Testa ovato-trigona, crassa (/ibhosa ; umbonihus sub-anticis antroswn curvatis ; lunula 

 cordaia, excavata, marginibus rotundatis, latere postico obtusangulo formante, siqjerfcie costis 

 regular ibus, rotundis, crebris, concenfricis, marghiibus interne denticulatis. 



Shell ovately trigonal, thick, gibbose ; umbones anterior and curved forwards ; luniile 

 excavated, cordate, its margins rounded ; the posterior side has an obtuse, oblique angle ; the 

 surface has closely arranged, rounded, regular, concentric costse ; the margins of the valves 

 are denticulated internally. 



Height, 6 lines ; opposite diameter, 5 lines ; diameter through the valves, 4 J lines. 



A short and very convex, thick, shell, with elevated umbones and slightly truncated 

 posterior border, which is pointed at its inferior extremity, near to which is a large fold of 

 growth . 



Geological Position and Localitg. Hampton, Cliffs near Bath ; collected by W. 

 Walton, Esq., who states that, having found it at the base of the cliffs, some doubt may 

 exist as to its real geological position. The mineral character of the specimen is ferru- 

 ginous and identical with that of the bed of Great Oolite Corals and of other shells which 

 unquestionably belong to the Great Oolite. 



AsTARTE iiusTicA, Waltou, MSS. Tab. XXXV, fig. 5 ; Tab. XL, f. figs. 8, 8 a. 



Testa parva, crassa, ovato-oblonga, plano-conveoea, umbonibus parvis, antemedianis, 

 acutis, margine, cardinnli brevi, subhorizontali, antice rotundato, basi subarciiato, marginibus 

 internis dentatis ; lateribus costis angustis imprimis regularibus, deinde inaqualibus. 



Shell small, ovately oblong, moderately convex, with thickened margins, internaly den- 

 ticulated ; umbones anterior to the middle of the valves, curved forwards, and acute ; hinge- 

 border short and horizontal, terminating in an obtuse angle. The anterior border is 

 roimded ; the lunule is only slightly excavated ; the base line is nearly straight ; the sur- 

 face of the valves has an obscure, posterior, oblique angle ; the costae are narrow, at first 

 regular, afterwards they become irregular and crowded. 



Length, 5 lines ; height, 4 lines ; diameter through the valves, 3 lines. 



Much variability exists in the prominence and arrangement of the costae, which are 

 sometimes very numerous and nearly obsolete, or they are distant and elevated. A little 

 species, allied to A. Voltzii, Roem., A. recondita, Phil., and the young of A. rhomboidalis, 

 Phil. ; neither of these species, however, has the test so thickened towards the margins. 



Geological Position and Localitg. The Porest Marble of Laycock, Somerset ; in the 

 cabinet of W. Walton, Esq. 



