34 BRITISH BELEMNITES. 



English and foreign palaeontologists, by which the name of B. acutus is fixed on the short, 

 compressed, pointed forms here described as containing two principal varieties. Equally 

 general is the consent to adopt as a synonym the first of three varieties, or rather species, 

 ranked by Blainville as B. brevis ; and by examination of foreign specimens referred to 

 that fossil by M. Hcbert, I find specimens of both varieties among them. In the 

 original description of Blainville the axis of the guard is described as medial throughout. 

 vSuch is, I think, never the case with English examples, though the excentricity varies. 

 D'Orbigny describes the axis as a little excentric. The same author gives a drawing to 

 represent a section of the phragmocone, with sides much less inclined than usual, and 

 with septa unusually distant. I have not yet obtained a good section of a phragmocone. 

 D'Orbigny refers to an angular variety in his own collection, ' Terr. Jur.' (pi. ix, figs. 13, 

 14). His specimens are a little bent, as sometimes occurs at Lyme Regis and Cheltenham. 

 This author notices the varying length of the guard in proportion to the diameter, the longer 

 specimens being supposed masculine. He did not perceive any grooves on his examples. 



Locality and Distribution. In Lower Lias beds, with Ammonites BucHandi, at the 

 base of Black Venn, Lyme Regis {Bay). In Lower Lias at Weston, near Bath [Sowerby), 

 and at Salford {Sanders). In Lower Lias beds at Hatch, near Taunton, with Amm. 

 obtusus {Moore). Antrim, in Lower Lias {Phillij^s). Near Cheltenham, in middle part 

 of Lower Lias {Strickland). Robin Hood's Bay, Yorkshire, in upper part of Lower Lias 

 {Oppel, Phillips). Thus in the British Islands it seems confined to Lower Lias. 



Foreign Localities. In Lower and Middle Lias (comuuuiicated by M. Hebert). La 

 Grange aux Bois, CharoUes, St. Cyr (Cote d'Or), Argenton. D'Orbigny gives other stations. 



Belemnites penicillatus, Sowerby. PL I, fig. 2. 



Reference. Belemnites penicillatus. Sow., *Min. Conch.,' p. 181, t. 590, figs. 6, 9, 1828. 



Guard. Short, much compressed, cylindroid, except in the posterior part, which 

 curves round to an obtuse, nearly central apex ; dorso-lateral grooves variable. 



Transverse section oval ; ventral aspect somewhat broader than the dorsal ; axis 

 nearly central. 



Greatest length observed, 2'75 inches; greatest diameter, 075 ; axis, LOO. 



Projwrtions. The longest diameter of the apex of the phragmocone being taken at 

 100, the ventral part is 48, the dorsal 52 ; the shorter diameter 76 ; the axis 150 in old, 

 under 300 in young specimens. 



Phragmocone. Almost truly conical, nearly straight on all sides ; its apex almost 

 central ; angle 24° ; section slightly elliptical, within the oval guard, which is much 

 thickened on the ventral and dorsal faces. 



