BELEMNITES OF THE OOLITE. 99 
compressed (often slightly bent or undulated) conical figure, terminated obtusely, obscurely 
striated lengthwise, and marked by six or seven furrows, viz. two latero-dorsal, very deep, 
much longer than the others, extending nearly the whole length of the attenuated part of 
the apicial region; four latero-ventral, of unequal length, the shortest and faintest being near 
the ventral line; and one medio-dorsal, always faint, and sometimes absent. 
The sections of the sheath vary according to the distance from the apex. The apicial 
line is straight. At the alveolar apex the external layer is oval, with diameters as 81 to 
100, the dorsal part being widest ; nearer the apex the figure is formed by two unequal, 
nearly semicircular curves, the ventral one being largest ; at the apex it is extremely com- 
pressed, with six or seven grooves. These grooves show in the central portions of every 
section of the sheath, and on breaking the specimens across a central prominence occa- 
sionally appears, but less distinctly than in the next species. The substance is compact 
and light-coloured, breaking nearly at right angles to the axis. 
Puragmocong. Oblique, with straight sides inclined at angles of 23°, the back 
and front inclined at 27°. Section elliptico-compressed, with diameters as 91 to 100. 
Greatest length observed 20 inches, of which the apicial line is 12. Greatest diameter 
on the middle alveolar region 2 inches. 
Proportions. ‘The diameter, v d, at the alveolar apex being 100, the lateral diameter 
is 81, the ventral radius is 40, the dorsal 60. 
Varieties. In most specimens the apicial region contracts remarkably at about one 
third of its length behind the alveolar apex, while before that line the alveolar region is 
nearly cylindroid; in others the whole figure more nearly approaches to a cone; the 
lateral profile of some is bent in a gentle arch, in others undulated. 7 
Locality. In the Lower Oolite formation (upper part) of Yorkshire, especially on the 
Scars at White Nab, south of Scarborough. (At Aalen in Wurtemburg, in the Lower 
Oolite formation, lower part, Voltz). In dr. Bean’s Collection, Yorkshire Museum, 
Scarborough Museum, and in the Author's Cabinet. In the Lower Oolite of Sherborne 
(Mr. Reed); and in the Lower Oolite of Leckhampton (M/r. Buckman). 
Observations. On specimens from White Nab, thin Oyster shells are found attached, 
and accommodated to the curved surface of the alveolar region of the sheath. In the 
alveolar cavity of another are crystals of sulphide of zinc. 
