1865.] TAWNEY RH^TIC BEDS AND SUrTON STONE. 85 



these three Muschelkalk species, as there is little apparent differ- 

 ence between them; but subsequently {" Infralias de Test de France," 

 in Mem. Soc. Geol. de Prance, 2nd series, vol. viii.) he deemed it un- 

 advisable to refer his species to them or the genus Ostrea, and it stands 

 as CarjpenteyiaHehertl. As the Sutton fossil bears considerable resem- 

 blance to Terquem's figui'es, it is with much diffidence that I con- 

 tinue to refer it to the Muschelkalk type ; the examination, however, 

 of several specimens having the same character of the umbonal region 

 leaves no doubt in my mind of its being an Ostrea ; and the descrip- 

 tion of 0. multicostata corresponds entirely with our shell. 



In some of my specimens the ribs are not so elevated and regular, 

 but more lamellar ; but these differences may be ascribed, I think, to 

 a young state ; others show a likeness in external characters to Pli- 

 catula Baylii (Terquem), but as I have not seen the hinge, I must 

 leave it to future researches to settle this point. 



Affinities. — This shell bears some resemblance to Ostrea ariefls of 

 the Angulatus- and Bucklandi-beds), but is still more nearly allied 

 to 0. Bhodani, Dumortier, from his Planorbis-zone *. He figures also 

 a fragment, which may be allied to this species, as passing up into the 

 Angiilatus-zone ; he considers it to be allied to the Muschelkalk spe- 

 cies, Ostrea coniplicata (Dumortier, Bass, du Rhone, pi. xxiii. fig. 6). 



14. Anomia socialis, spec. nov. PI. III. fig. 10. 



Provisionally I call this shell Anomia, from its shell-structure ; there 

 are not, however, in my possession data enough to safely determine 

 or describe the specific characters. Its abundance, however, in some 

 localities where it occurs in groups, renders it a most noticeable 

 shell ; I therefore name it as above. Length 11 inch. 



Locality/ a7id position. — Sutton series at St. Mary Hill. Common. 



This shell has a great resemblance to Ostrea subanomia (Miinst.) 

 from the Muschelkalk, but I cannot with any surety refer it to that 

 species. 



15. Pinna insignis, spec. nov. PI. III. fig. 5. 



Shell thin, acute at the umbo, broadly wedge-shaped ; posterior 

 extremity gaping, strongly rounded, and truncated. Dorsal edge 

 thickened and well defined. Surface smooth, with broad, wavy, con- 

 centric folds. Length 7 to 8 inches ; breadth 4 to 5 inches. 



Position and locality. — Sutton and Southerndown series at Sutton 

 and Dunraven. 



This shell is most usually found in quite a fragmentary condition ; 

 it attained a large size, and was a widely gaping form. 



Notwithstanding the imperfect state of my examples, I am obliged 

 to create a new species. It differs considerably from Pinna semi- 

 striata, Terquem (Pal. de Lux. pi. xxii. fig. 1), being comparatively 

 wider, and the concentric folds do not show the same disposition. 

 It is also more pyramidal than Pinna papi/racea, Stopp., and the 

 shell is not so extremely thin as in that species. 



'^ Dumortier includes in the Planorbis-zone- beds contixiningPectenVahnie7isis 

 and Plicatula intusstriata abundantly. 



VOL. XXII. — PART 1. H 



