14 BRITISH FOSSILS. 



dant in the bed in which it was found, and my colleague, Mr. Etheridge, 

 is of opinion that it belongs to that species, "though it has strong 

 affinities with B, Foumeliamts (D'Orb)." 



In the collections of Liassic fossils to which I have referred, and 

 chiefly in that of Mr. Day, there is a series of fragmentary Belemnitic 

 remains, consisting for the most part of ink-bags, associated sometimes 

 with more or less of the proostracum, sometimes with hook? and imper- 

 fect beaks in very nearly natural relative positions ; sometimes with 

 more or less of the phragmocone, but hardly ever with a guard. That 

 these belong either to the species already described, or to a closely 

 allied one, is highly probable ; in any case, the study of the features 

 presented by some of them may help to throw light on the structure of 

 the Belemnitidce generally. 



1. In a great many Belemnites I have observed conothecal stria? 

 having the arrangement described by Voltz (Plate I., figs. 6 and 7) ; 

 but a large phragmocone from the Ammonites obtusus zone in the Rev. 

 Mr. Montefiore's collection, the apex of which is broken off, but which 

 still has a width of 2^ in. and a length of five inches, exhibits a dis- 

 position of the conothecal lines different from any which 1 have met 

 with, or seen described. (Plate I., fig. 4a.) 



Only a small portion of the conotheca is preserved in this specimen, 

 coating the cast of a phragmocone in calcareous spar, which exhibits 

 the remains of the siphuncle very distinctly along the middle line of 

 that face of the specimen which is turned to the right in the figure. 

 This is, therefore, the ventral line, and the face turned to the eye is the 

 left lateral face of the phragmocone, the figures not having been 

 reversed. Now it will be observed that instead of one asymptote as 

 usual, there are two, separated by an interval equal to about th of the 

 circumference of the phragmocone. Sharply arched hyperbolic lines, 

 the ends of which pass into the asymptotes, and which are convex 

 upwards, occupy the space between the two asymptotes ; of which the 

 one may be termed the dorso-lateral, the other the ventro-lateritl 

 asymptote. 



Faint curved lines run obliquely upwards from the dorso-lateral 

 asymptote towards the middle line of the dorsal region, so that the 

 dorsal area of the conotheca doubtless had its usual set of upwardly 

 convex curved lines. The ventral area, on the other hand, enclosed 

 between the ventro-lateral asymptotes, exhibits no very distinct 

 markings, though faint indications of transverse lines are discernible. 



The conotheca in this case, therefore, differs from the ordinary type 

 in having three sets, one medio-dorsal and two lateral, of upwardly 

 convex curved striae, and in possessing four asymptotes instead of 

 two. 



According to D'Orbigny (" Paleontologie Franaise," Terrains Juras- 

 siques, Atlas, PI. 16, fig. 1), the conothecal lines of Belemnites 

 Puzosianus have the ordinary arrangement, and the lateral bands of 

 the pro-ostracuni of this species would seem to correspond with the 

 asymptotes. 



If the arrangement of the conothecal lines, then, indicates the form of 

 the pro-ostracum and vice versa, the majority of Belemuites ought to 

 have a two-banded pro-ostracum like that of B. Puzosianus ; and, on 

 the other hand, the peculiar arrangement of the conothecal lines of the 

 present phragmocone ought to indicate that it was associated with a 

 different kind of pro-ostracum ; and, so far, ihere may be ground for 



