BELEMNITELLA. 7 



impressed line runs down the dorsal side of the cavity. The vascular impressions are 

 usually well-marked, and cover a large part of the surface, they branch off from a pair of 

 double lines, which commence near together on the two sides of the back, and separate 

 gradually as they extend downwards to near the point. 



B. mucronata is nearly alhed to B. lanceolata ; it may be recognised by a more 

 cylindrical form with a distinct mucro, by its well-marked vascular impressions, and by 

 the eccentricity of the alveolar cavity. 



In a fine specimen from Norwich, measuring 3^ inches in length, the greatest diameter 

 is fAs of an inch, and the fissure extends externally fths of an inch. But all the 

 specimens found in this country are broken off at the top, where the walls of the alveolus 

 are very thin. They are found in the Maestrict Sandstone with the upper part much 

 better preserved, the whole being 6 inches long, the alveolus spreading out at top to a 

 width of above an inch, and with an external fissure 2^ inches long. 



Found everywhere in the Upper Chalk of the South of England, and particularly 

 abundant in Norfolk. It is also found in the Upper Chalk of France, Germany, Belgium, 

 Sweden, and Russia. Also in the Cretaceous Sands of Maestrict and Ciply near Mons, 

 and at Faxoe in Denmark. 



2. Belemnitella lanceolata, ScMotheim, Sp. Plate I, figs. 4 — 6. 



Belemnites, 2" species: Breyn, de Belemnitis, figs. 7 — 10. 



— LANCEOLATUS, Schlotheim. Petrefactenkunde, p. 49, No. 8. 



— MUCRONATUS, Brong. and Cuvier, t. iii, fig. 1 ? 



— — Blainville. Belemnites, t. i, fig. 12. 



— — Sowerby. Min. Conch., t. 600, fig. 1, excluding all the 



other figures. 



— — Woodward. Geol. Norfolk, p. 49. 



Belemnitella mucronata, var. fusiforme, D'Orbigny. Geol. of Russia and the 



Ural Mountains, vol. ii, t. xliii, figs. 2 

 and 3. 



B. Testa elongatd, fusiformi ; antice suhdilatatd, Jlssuratd ; postice acuminatd ; 

 aperturd suhrotundd ; alveolo conico^ centrali. 



Shell elongated, fusiform, widening at the opening, then somewhat contracted, and 

 again enlarging to about two thirds its length, whence it gradually tapers off to a 

 point. Alveolus slightly oval above, circular below, forming a regular hollow cone, of 

 which the apex with an angle of 20° is nearly on the central axis of the shell ; the 

 alveolar cavity is lined by a distinct shelly layer, faintly marked by numerous horizontal 

 rings, very near each other in the lower part, and becoming gradually more distant 

 upwards, and is slit down its anterior side by a fissure which extends within nearly to the 

 apex of the cavity; but is partially closed on the outside by the new layers of shell, which 

 in old specimens cover about half an inch of the lower part of the original fissm-e. Another 



