Belemnites. 



MOLLUSCA. 



41 



O. Gesneri. Martin, Pet. Derby, pi. 38, fig. 1, 2. Fle- 

 ming, Brit. An. p. 239- Phillips, Geo. of Yorkshire, II. 

 p. 239, pi. 21, fig. 6. 



Shell curved, conical, with about thirty longitudinal, close, 

 acute, regular ridges and rounded furrows ; siphuncle placed 

 nearly marginal ; section slightly ovate. 



Found in the Carboniferous Limestone of Derbyshire, 

 Middleton Tyas, Northumberland ; Cumberland ; Isle of Man ; 

 and BoUand, Queen's County. 



19. O. RUGOSA — The Rugged Orthocera, pi. XXVIIl. 

 fig. 8. 



Orthocera rugosa. Fleming, Brit. An. p. 239. ib. Ann. 

 Phil. V. p. 203. Phillips, Geo. of Yorkshire, p. 239, pi. 21, 

 fig. 16. 



Shell subcj'lindrical, slightly arcuated with annular, undu- 

 lating, somewhat distant ridges, crossed at intervals by strong 

 striiE producing a knotty appearance, the intervening spaces 

 with longitudinal, tuberculated, subechinated lines ; siphun- 

 culus minute, and situate close to the edge ; between each 

 of the transverse annulations are two chambers. 



Found in the Carboniferous Limestone of Northumberland. 



20. O. Cornu-Ibex. — The Ibex-Horn Orthocera, pi. 

 XXVIIL fig. 13. 



Orthoceras annulatum. Phillips, Geo. of Yorkshire, II. 

 pi. 21, fig. 10. 



Shell a little arcuated, cylindrical, with manj' slightly 

 undulous smooth annulations ; intervening spaces smooth. 



This shell differs from the O. unnulata in being more 

 bent, in being greatly thicker in proportion to its length, and 

 in the rings being closer. 



Found at High-Green-Wood. 



21. O. UNGUIS.— The Claw Orthocera, pi. XXVIH. fig. 16. 

 Orthoceras unguis. Phillips, Geo. of Yorkshire, II. p. 238. 



fig. 2. 



Shell smooth, abruptly arcuated towards the thicker end ; 

 septa numerous ; section orbicular. 



Found at Bolland, Queen's County, Ireland. 



22. O. DENTALOiDEUM. — The Tooth Orthocera, pi. 

 XXVIH. fig. 18. 



Orthoceras dentaloideum. Phillips, Geo. of Yorkshire, II. 

 p. 239, pi. 2L fig. 12. 



Shell greatly curved, and tapering gradually, with nume- 

 rous small longitudinal ridges and furrows. 



Found at Bolland, Queen's County. 



Genus XL— BELEMNITES.— iawarcA. 



Shell straight, conical, elongated, capable of being 

 separated into two parts, the outer one a solid sheath, 

 produced above, and excavated, with a conical cell 

 beneath ; the inner nucleus conical, and multilocular, 

 divided by numerous transverse septa, perforated by a 

 central tube. 



SECTION. 



-SHELLS LANCEOLATE. 



1. B. LANCEOLATOs The Spear-Shaped Belemnite, pi. 



XXIX. fig. 1. 



Selemnites lanceohtus. Sowerby, Min Conch. VI. p. 208, 

 pi. 600, fig. 8, 9. 



Shell smooth, subfusiforra, greatly elongated, one-half 

 narrow, the other thickened, and gradually tapering to a 

 point ; each side with a double obsolete furrow ; base ob- 

 scurely triangular, base convex, or conical. 



Found in the Chalk at Hamsey. 



2. B. GRACILIS. — The Slender Belemnite, pi. XXIX. 

 fig. 1.3. 



Belemnites gracilis. Phillips, Geo. of Yorkshire, I. p. 138, 

 pi. 5, fig. 15. 



Shell smooth, fusiform, thick at one end, and graduallj' 

 tapering to a somewhat obtuse point, and extremely slender at 

 the other ; section orbicular. 



Found in the Oxford Clay at Scarborough. 



3. B. ATTENUATus. — The Attenuated Belemnite, pi. 

 XXIX. fig. 3. 



Selemnites attenuatus. Sowerby, Min. Conch. VI. p. 176, 

 pi. 589, fig. 2. 



Shell subfusiform, somewhat quadrangulai', tapering slightly 

 towards the base, contracting abruptly a little above the 

 centre, from which to the somewhat obtuse apex, it is nearly 

 cylindrical, and frequently striated ; each side is provided 

 with an almost obsolete, double, longitudinal furrow, and a 

 sulcus in front extending a short way from the base. 



Found at Folkstone. 



4. B. Allani. — Allan's Belemnite, pi. XXIX. fig. 8. 



Belemnites Allani. Fleming, Brit. An. II. p. 240. Belem- 

 nite, Allan, Trans. Royal Soc. Edin. IX. p. 407, pi. 25. 

 Mantell, Geo. of Sussex, p. 201, pi. 16, fig. 1. 



Shell smooth, cylindrical ; apex conical, with a slender 

 produced point; alveolus conical, acute, with a sublateral 

 point ; a longitudinal section exhibits a small tube extending 

 from the alveolus to the apex of the spathose part. 



Found in Chalk at Brighton and Lewes. 



5. B. PENICILLATUS. — The Pencil-shaped Belemnite, pi. 

 XXIX. fig. 5. 



Belemnites penicillatus. De Blainville, Mem. sur les 

 Belem. p. 89, pi. 3, fig. 7- Knorr, Part II. pi. 1,* fig. 1 to 4. 

 Sowerby, Min. Conch. VL p. 181, pi. 590, fig. 5, 6. 



Shell compressed, short, tapering in a very gradual man- 

 ner towards the superior extremity, near which it is abruptly 

 contracted to an almost central, longitudinally striated or 

 sulcated obtuse point ; cavity of the opposite extremity 

 rather deep. 



Found in the Chalk in Shorne Cliff. 



6. B. GRANULATus The Granulated Belemnite, pi. 



XXIX. fig. 6, 7 



Belemnites granulatus. De Blainville, ^lem. sur les 

 Belem. p. 63, pi. 1. fig. 10. Sowerby, Min. Conch. VI. p. 

 207, pi. 600, fig. 3, 5. 



Shell subcylindrical ; surface covered with small granula- 

 tions, and the impressions of veins ; tapering rather abruptly 

 to an obtuse mucronated apex ; sides with a double longitudi- 

 nal nearly obsolete furrow. 



Found in the Chalk at Andover and Bridgewick Pit, near 

 Lewes. It is said to occur in St Peter's Mountain, near 

 Maestricht. 



7. B. FUSiFORMis. — ^The Spindle-Shaped Belemnite, pi. 

 XXIX. fig. 14. 



Belemnites fusiformis. Parkinson, Org. Rem. III. p. 127, 

 pi. 8, fig. 13. Fleming, Brit. An. p. 240. Phillips, Geo. of 

 Yorkshire, L p. 123, pi. 3, fig. 1. 



Fusiform, somewhat compressed in the fore part ; abruptly 



