234 



Sphaerulites. 



foliacea. . the only species known. 

 Radiolites. 



rotularis. . valves forming opposite, short, nearly equal cones. 

 ventricosa. . lower valve turbinated, upper valve ventricose ; 

 opercule retuse. 



Calceola. 



sandalina. . formed like the point of a slipper : the only species 

 known. 



Birostrites. 



incequiloloba. . two long, conical, rostriform, unequal valves, 

 disposed in an obtuse or rather open angle, and united at 

 their base, but the edge of one overwrapping that of the 

 other. 



Discina. 



ostreoides. . small, flat, ovato-rotundate ; adhering to the stones 

 on the sea coast. 



Crania. 



personata. . orbiculate ; the upper valve conical ; the lower valve 

 with three little pits. 



nummulis. . suborbicular, free, flat, radiately striated within ; 



three little pits ; margin thick, not crenulated. 

 Only one valve known, perhaps the under, but with no marks 



of adherence on the back. . Sweden. 

 Nummulis Brattenburyii. 



Parisiensis. . resembles the former ; but shows marks of ad- 

 herence. 



antiqua. . lower valve adhering only by its beaked termination 

 under the hinge, striated beneath concentrically ; three 

 pits ; the upper valve very convex, with three impressions 

 answering to the pits of the under valve, . Nehou. 



striata. . very small, rounded ; lower valve flat, subtruncated, 

 adherent ; prominent calluses within ; the free valve orbi- 

 cular, back raised, radiatedly striated. 



Orbicula. 



Norwegica : 



Patella aiiomala, Mull. 



Terebratula. 



Smooth, not grooved, 



subundata. . subglobose, smooth ; with fine concentric striae, 

 margin subundulated ; valves nearly equally ventricose. . 

 Warminster, 



cornea. . sub rotund, subdepressed, smooth ; with five concen- 

 tric striae ; beak elevated, incurved ; foramen very small. . 

 near Norwich. 



