84. 



BRITISH BELEMNITES. 



extended in a slender cylindrical form backward, and marked with two long, con- 

 spicuous, lateral grooves. (No striae seen.) 



In the transverse section of the sheath, immediately behind the alveolar region, the 

 outline is oval, the dorsal aspect being widest. Ventral radius 45 , dorsal radius 55, 

 transverse diameter 80, axis 850. 



Phragmocone. Unknown. 



Locality. Only one specimen has come to my knowledge, — from Nailsworth, in the 

 sands which cap the Lias [Mr. C. Moore's Cabinet). 



Remarks. Belemnites acuarius is a name applied to many forms of Belemnite, one of 

 which has been already referred to as allied to B. tubularis — by some thought identical with 

 it. Quenstedt's figure, now referred to, appears certainly to agree with the Nailsworth 

 specimen, and with no other that I have seen from English localities. Another figure of 

 Quenstedt's may probably be regarded as belonging to the species {B. acuarius longi- 

 sulcatus, 'Cephal.,' pi. xxv, fig. II), and fig. 12 of the same plate, which is striated, may, 

 perhaps, be added to this reference. I shall be glad to hear of more specimens from the 

 EngUsh Lias and Liassic Sands. • 



It appears necessary to mark this by a definite name — '"acuarius" being already 

 used in the sense of D'Orbigny, " macer" being also employed by Mayer. I propose the 

 &i^\\}(\&V' sulci-stylus" for the smooth, compressed, grooved forms, with cylindroid extension 

 of the guard, not capable of heiwg flattened by pressure. I regard this flattening as a mark 

 of imperfect original calcification characteristic of a small number of these elongated 

 Belemnites, chiefly of the Upper Lias. 



Belemnites elegans, Simpson. PI. XX, fig. 50. 



Reference. Simpson's 'Lias Belemnites,' No. 40, p. 31, 1855. 



Guard. Compressed, subhastate ; cylindroidal in the post-alveolar region, tapering 

 from thence to an extended, striated, pointed apex ; slight traces of short dorso-lateral 

 grooves at the apex ; on some specimens long, lateral, shallow grooves. 



Transverse section elliptical till near the apex, where it is obscurely trilobed ; axis 

 a little excentric. 



Longitudinal sections show the axis to be nearly straight, and the young to have had 

 more uniformly tapering sides. 



In young specimens the proportion of the axis appears to be nearly the same, or 

 rather longer, but the general figure is more uniformly tapering. 



Dimensions. The largest specimen from Robin Hood's Bay which I have seen is in 

 the Whitby Museum, No. 967, 5 2 inches long, and 65 in diameter at the alveolar 



