THE COKALLIAN ROCKS OF ENGLAND. 395 



one is probably the operculum of JV. Guerrei, the only species known 

 in the rock. 



In the Coral Rag of Upware, Cambridgeshire. 



Trochtts aytonensis, spec. nov. PI. XIV. fig. 1 d. 



Spiral angle 60°. Each whorl ornamented with a nodular band 

 at the base, and three rows of tubercles above ; base smooth, imper- 

 forate. Length 1| line. 



In general shape and ornaments this is near to T. carinellaris 

 (Buv.) ; but there are more rows of tubercles in that species. 



In the Hag of Ayton, associated in the figured block with Littorina 

 muricata, Cerithium inornatum, and Eucyclus Buvignieri. 



Patella mosensis, Buvignier. 



"We have inserted this in the list of Upper Calcareous Grit forms 

 in spite of the absence of any remains of a muscular impression, 

 which has led M. Deshayes to reject similar fossils from the Mol- 

 lusca. We could scarcely expect to find such impressions in the 

 fossils, when they are so difficult to perceive even in the recent 

 shells of several patelloid mollusca. 



GASTKocn^ENA cartnata, spec. nov. PI. XY. fig. 5. 



Height half the length ; valves moderately inflated ; umbones | 

 the length of the shell from the anterior end, small, approximate ; 

 posterior end obliquely truncated, having one minor keel running 

 from the umbo nearly parallel to the hinge-line, and enclosing a 

 curved area, and one larger, running from the umbo to the ventral 

 margin ; area behind this keel smooth ; gape reaching the middle 

 of the ventral margin. Length 4 lines. 



This is nearly allied to G. corallensis, but differs in having the 

 first keel less conspicuous, and in having no ornament between the 

 keels. 



Among the corals in the Rag of Westbrook, Wilts. 



Tancredia disptttata, spec. nov. PI. XIV. fig. 7. 



Height | the length ; valves not very convex, most so opposite 

 the umbo ; umbo nearly median, slightly posterior ; ventral margin 

 uniformly convex, curving rapidly anteriorly to meet the sloping 

 dorsal edge ; posterior end more convex on the surface, having a 

 very slightly flattened space diverging from the umbo ; posterior 

 margin rounded. Length 1-^ inch. 



This differs from the common T. planata, associated with it, by 

 its greater comparative length and its more pointed anterior end. 

 Its uniformity of outline gives it something of the appearance of a 

 Pleuromya. 



In the Osmington Oolite. 



i ^' 



Lucina aspera, Buvignier. PL XIV. fig. 8. 



The shells recorded under this name may perhaps be rightly iden- 



