BELEMNITES OF THE LIAS. 43 



portant, but there are peculiarities in the description of M. Voltz which seem to require 

 attention. He notices in his variety a the phragmocone as sensibly curved towards the 

 ventral side ; in a section of a specimen from Gundershofen I find this curvature, as (indeed 

 his figures (pi. ii, d" and d"') show it to be) very slight. He mentions also a curvature 

 of the axis of the guard, and it appears in the figures quoted ; it is only just traceable in 

 my specimen. There is no sensible change of figure from youth to age, except that the 

 diameter grows larger in proportion. 



In his variety b (Voltz, fig. 4, d) he figures the axis as decidedly curved, and passing 

 very near to the ventral face in all the posterior parts ; the phragmocone is represented as 

 very sensibly curved ; neither in b nor c are either ventral or lateral grooves. These varieties 

 are not larger than var. a. In specimens which I possess from the Eston Nab Ironstone- 

 beds, Frees, and Glastonbury, these characters are found precisely as in Voltz's figure 

 and description, except as to the lateral grooves, which are traceable, more or less 

 distinctly, in most cases. These individuals are larger than any of the specimens 

 of Voltz, and correspond in magnitude with others from Alderton, in Gloucestershire, 

 in which the lateral grooves are quite distinct. Admitting all these forms to belong to 

 the species so well examined by M. Voltz, we have the following result for the British 

 deposits : 



Var. a = var. a, Voltz. Guard having an acute conical termination, without 

 distinct inflexion or grooves. Fhragmocone very slightly incurved (Fl. IV, fig. 9 a,b). 



Locality. In England, the Belemnite-bed under Golden Cap, Lyme Regis, base of 

 Middle Lias ; in Germany, Gundershofen, Upper Lias. 



Var. jS =z Var. b, c, Voltz. Guard terminated by a summit more or less prominent, 

 acute, and inflected towards the back ; no distinct lateral grooves. Fhragmocone dis- 

 tinctly incurved (Fl. IV, fig. 10a). 



Locality. In England, Frees, Salop, in Middle Lias {Morton). Eston Nab, 

 Yorkshire, in ironstone of the Middle Lias {Phillips). Glastonbury, in Middle Lias 

 {Phillips). 



Var. y. Guard terminated by a submucronate summit, more or less prominent 

 from the ventral half of the substance, and more or less inflected towards the back. 

 Lateral furrows near the back always traceable (Fl. IV, fig. 10 b, 10 c, 10 d). 



Greatest length observed, 2*5 inches ; greatest diameter, 0-6 inch. 



Longitudinal sections show the axis to be excentric, arched, and much nearer to the 

 ventral side, remarkably so at the apex of the phragmocone, least so towards the apex of 

 the guard. Transverse sections show the sides to be flattened, so that the sparry substance 

 is thinner there over the alveolus. The lateral grooves at the apex are continued more or 

 less distinctly into these flattened spaces. 



