Okthocera. MOLLUSCA. CEPHALOPODA. 239 



** Striated transversely. 



10. O. striata. — Nearly cylindrical, septa numerous, deep ; syphon nearly 

 central ; surface regularly striated transversely. — Sower. M in. Conch, t. lvii'i. 

 Flem. Wem. Mem. iii. 90. — Transition Limestone, Cork. In the clay-slate of 

 the same formation, at the Cove of Cork, another species occurs, the charac- 

 ters of which are not established. 



1 1. O. Steinhaueri — Tapering ; chambers deep, partitions distant, even 

 edged, circular ; syphon close to one side ; striae of the surface regular and 

 even — Sower. M in. Conch, lx. f. 4. — In Carboniferous Limestone. 



12. O. gigantea — Shell gradually tapering, finely striated, aperture up- 

 wards of 8 inches in diameter ; septa direct, numerous, deep ; syphon a small 

 distance from the centre — Sower. Min. Conch, t. ccxlvi. — In limestone of 

 the Old Red Sandstone, Dumfriesshire. 



*** Surface with transverse ridges. 



13. O. sulcata — Shell tapering ; ridges waved and striated ; syphon small, 

 central. The length of one specimen is 2 inches and , 6 ths, diameter at 

 the base T ' 3 ths, and at the apex T 9 5 ths. It contains thirty-one ridges, which 

 are twice waved in going round the shell : both the ridges and intervening 

 grooves are finely striated — lire's Ruth. 300, t. xvi. f. 2. Flem. An. Phil. v. 

 202, t. xxxi. 6. — In slate-clay of the Coal Formation. 



14. O. undata — Shell tapering, ridges waved and smooth ; pipe small, cen- 

 tral. In a specimen 1 inch and , 2 ths in length, it is , 7 ths in diameter at 

 the base, and upwards of T * s tha at the apex ; witli eleven ridges, more deep- 

 ly waved, and less numerous than the preceding. There is the appearance 

 of an epidermis of a black colour, and obscurely striated ; where the shell is 

 exposed, both the ridges and the grooves are perfectly smooth. An imper- 

 fect specimen of an Eschara adheres to the shell — Flem. An. Phil. v. 203 



In slate-clay of the Coal Formation. 



15. O. annularis.— Subcylindrical ; ridges distant, nearly even and smooth. 

 The largest portion of the shell which I possess is about ] inch in length, 

 and upwards of T 3 5 ths in diameter ; ridges nearly ^th distant ; more obtuse 

 than the preceding, with at least two chambers in the interval.— Flem. Ann. 

 Phil. v. 203.— In Carboniferous Limestone. 



10. O. annulata.— Tapering, subcompressed, with strong, waved, slightly 

 oblique ridges, and intervening strife : syphon sublateral ; a space near the 

 aperture without ridges.— Sower. Min. Con. t. cxxxiii.— Carboniferous Lime- 

 stone, Colebrookedale. 



17- Q.rugosa. — Subcylindrical; ridges waved, and tuberculated with longi- 

 tudinal lines ; syphon minute, and placed close to the edge. The length of a 

 specimen which I possess is 1 J inch ; the diameter T G 5 ths ; the ridges are T 2 a ths 

 asunder, and contain two chambers in the interval.— Flem. Ann. Phil. v. 203. 

 —In Carboniferous Limestone. 



**** With longitudinal planes or furrows. 



18. O. Gesneri — Conical, with numerous longitudinal furrows, regularly 

 concave and close.— Mart. Pet. Derb. t. 38. f, 1, 2 — In Carboniferous Lime- 

 stone, Derbyshire. 



17- O. angularis.— Nearly cylindrical, angular, with about 16 smooth lon- 

 gitudinal planes ; syphon small and lateral. I possess about half an inch of 

 this shell, which is nearly of equal thickness, scarcely exceeding the tenth of 



an inch in diameter Flem. Ann. Phil. v. 203. t. xv. f. 10 — In Carboniferous 



Limestone. 



