1865.] TAWNEY EH^TIC BEDS AND SFTTON STONE. 87 



crumbled on being moved. The concentric folds of growth were 

 distinct and strong. 



It approaches nearest to 0. crassissima, Ag. ; but the pallial line 

 does not quite agree with that species. 



•21. Caedita ? EHOMBOiDALis, spec. noY. PI. IV. fig. 6. 



Shell convex, rhomboidal ; a rounded ridge extends from the 

 umbo to the posterior margin. Dorsal and ventral margins nearly 

 parallel; posterior end of shell vadest. Umbones placed far for- 

 wards, somewhat recurved. Hinge-line straight. Interior margin 

 of the shell delicately crenate. Surface with regular, elevated, con- 

 centric lines, which cross over* the rounded ridge, and, by a sharp curve, 

 reach the dorsal margin. Length 1 inch ; breadth -Jrds of length. 



Locality and ■position. — Sutton quarries, Sutton series. Common 

 near the base. 



The shell- substance is rarely found. The mould of the inside 

 drops out of the cast, leaving the impression of the exterior surface : 

 from this gutta-percha casts may easily be obtained. 



Not having seen the hinge-teeth, I am uncertain of the genus. 



It somewhat resembles Cardita tetragona, Terquem ; I therefore 

 refer it provisionally to that genus. 



22. MODIOLA IMEEICATO-EADIATA, SpCC. UOV. PI. lY. fig. 8. 



Shell small, convex, transversely oblong, comparatively thick. A 

 rounded elevated dorsal ridge extends from the umbo to the posterior 

 margin. Posterior margin rounded ; ventral slightly concave. Sur- 

 face of shell ornamented with numerous radiating rounded ribs, which 

 are slightly wavy and sometimes forked, crossed by a few growth- 

 lamellae. Umbones obtuse, placed far forwards. Length 0-6 inch ; 

 breadth frds of length. 



Locality and position. — Sutton quarries, Sutton series. Common 

 near the base. 



The ornamentation is like that of the Oolitic species M. pul- 

 cherrima ; it reminds us also of Mytilus furcatus, but is very much 

 smaller, the margin not so concave, &c. 



23. AsTAETE DuNCANi, spcc. uov. PI. lY. fig. 4. 



Shell convex, rhomboidal, inequilateral, widest at the posterior 

 end ; posterior margin rounded and forming rather less than a right 

 angle with the ventral margin. Surface of shell with strong con- 

 centric lines of growth wider apart posteriorly, and intervening finer 

 ones. Umbones placed far forwards. Length ^ inch ; breadth Jths 

 of length. 



Locality and position. — Sutton quarries, Sutton series. 



The genus of this shell is not quite certain, my specimen not 

 showing the hinge-line 



It is named after our Secretary, who has kindly undertaken the 

 description of the corals from the Sutton Stone. 



24. Ctpeina noemalis, spec. nov. PI. lY. fig. 7. 

 Shell suborbicular, convex, inequilateral, thick, Umbones slightly 



n:2 



