42 BRITISH BELEMNITES. 



Longitudinal sections show the axis to be always more or less curved, especially 

 near the apex, and nearer to the ventral than the dorsal face ; much nearer towards the 

 apex. Transverse sections show a tendency to flatness of the sides, so as to give an 

 approach to a certain squareness in the outline. Diameters nearly equal. 



Size rarely exceeding 2 inches ; diameter rarely exceeding | of an inch. 



'Proportions. The normal diameter being 100, the ventral part of it is 37, the dorsal 

 part 63 ; the transverse diameter is also 100 (more or less). The axis, 200 to 300. 



Phragmocone. Oblique, with a circular section, more or less inflected towards the 

 apex, and terminated by a sphericle. Concamerations numerous ; siphon not affecting the 

 sutures of the cells. Angle 25° to 27°. 



Varieties. According to M. Voltz, who described this species after inspection of 

 more than fifty individuals from Gundershofen, in Upper Lias, three varieties occur : 



(a) Guard somewhat depressed, its summit acutely conical, without distinct 

 inflexion or furrows (Voltz, pi. ii, fig. 2). 



(b) Summit submucronate (Voltz, pi. ii, fig. 4). 



(c) Summit mucronate, axis very near the ventral side (Voltz, pi. ii, fig. 3). 



Observations. The species called breviformis by Voltz, if allowed to include all the 

 varieties w^hich have been referred to it, must be quoted from Middle Lias, Upper Lias, 

 and Inferior Oolite. Voltz supposes that Belemnites brevis, var. b, of Blainville (pi. iii, 

 fig. 2), may be identical with B. breviformis, var. c, Voltz ; and as far as the figure of 

 Blainville is evidence, his opinion seemed just. But by late researches of M. Hebert, who 

 has examined many specimens of the variety mentioned by Blainville, it seems to be 

 really a distinct species, for which the name of brevis may be retained. This author is of 

 opinion that £. brevis, D'Orb. (' Pal. Fran?., pi. ix, figs. 1 — 7 ; in the text it is called 

 jB. abbreviatus), is identical with the species of Voltz. 



Varieties. I possess some half-dozen individuals of this species from Lyme Regis, 

 some of which were collected by myself from the Belemnite-bed, mider Golden Cap ; others 

 supplied by Miss Anning, probably from the same locality. From Gundershofen M. Voltz 

 was so good as to send me five specimens, showing the varieties a, b, c, which he 

 includes in the species. M. Hebert also sent me a larger series from the same place. It 

 is evident that these all correspond, the English specimens being chiefly of the first variety 

 (a) of Voltz. All agree in a lanceolate figure, with an approach to cyhndrical section (or 

 a little planate on the sides), and in a summit quite free from systematic grooves. The 

 apex tends to recurvation (and in var. b, c of Voltz to submucronation). The points of 

 doubt which arise on comparison of specimens from England and Germany are unim- 



