40 BRITISH BELEMNITES. 



the phragniocone is seen in section, and thirty septa are traceable in a length of 0"6 inch. 

 They are converted to iron-pyrites, and seem to be single plates with long flanges. The 

 conotheca is traceable, covered by the thin expansion of the guard. [Quenstedt ('Jura,' 

 p. 137) conjectured that Orthoceraiites elongatus of De la Beche might be the phragmocone 

 of this species, with its septa very much further apart than is usual in the genus. But 

 that fossil constitutes the Xiphoteuthis of Huxley.] The alveolar angle is 18° or 20°, but 

 by compression often appears larger. 



Variations. Considerable in respect of the general form and degree of compression of 

 the guard, the excentricity of its axis, and the distinctness of the two lateral furrows in 

 the lower part of the alveolar region. (For notices of these circumstances, see a, 



A 7' SO 



a. Guard with only very faint traces of lateral furrows, and the axis but little 



excentric. 



/3. Guard distinctly marked on the alveolar region with two narrow furrows, which 

 vanish on the expanded posterior part. Axis but little excentric. Transverse sections 

 very slightly oval. 



Young specimens are elegantly fusiform, and without lateral furrows; with age, 

 laminae are added over all the surface, so as to elongate the apicial region and carry 

 back its swollen part, while in front of this the long, generally furrowed part is of nearly 

 equal diameter. Substance a clear yellowish spar, often white externally, easily decom- 

 posing in the contracted part, so as to lose the alveolar portion. 



■y. Guard compressed, marked with two lateral furrows ; axis excentric. owing to the 

 thickening of the outer layers on the dorsal aspect. This appears to be the B. spadix ari 

 of Simpson's * Lias Fossils,' p. 30. 



S. Guard subcylindrical, without lateral furrows ; axis very excentric. (Probably B. 

 fusteolus, Simpson, ' Lias Foss.') 



The varieties y and ^ are not in general so much contracted in the post-alveolar region 

 as the others. 



Ohservations. Sowerby, who gives good figures, observes, " It is very possibly the 

 young of Belemnites elongatus" The remark is not applicable to the fossil which he 

 figures under that name, but there are elongate subcylindrical forms at Lyme Regis, 

 which may perhaps, on further research, be proved to belong to this species grown old. 

 The geological range does not, according to present information, reach the Upper Lias in 

 England. 



Localities. In Lower Lias, Hatch, near Taunton, with Ammonites raricostatus and 

 A. ohtusus [Moore). In the upper part of the Lower Lias, under Huntcliff", Yorkshire 

 {PJiillips). In the upper part of the Lower Lias of Robin Hood's Bay, Yorkshire [Bhillips, 

 Cullen). In the Belemnite-bed at the base of Middle Lias, Golden Cap, Lyme Regis 

 {Anninq, Bay, Etheridge., Phillips). In ironstone-beds east of Staithes, top of Middle 

 Lias, Yorkshire {Phillips). 



