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BRITISH BELEMNITES. 



figure have been obtained from the laminated Oolite of Solenhofen, the laminated Clay of 

 Christian Malford, and the laminated beds of Lias in Dorsetshire and Yorkshire. Three 

 different forms are thus put in evidence ; we may add, as a fourth, the elongate shape of 

 Xiphoteuthis. 



In the preceding sketches the conotheca is supposed to be opaque, so that the interior 

 septa are not seen. The aspect is dorsal. 1 is from Belemnites hast at us, from 

 Solenhofen. 2, B. Owenii, from Christian Malford. 3, Xiphoteuthis elongatus, from 

 Lyme. 



The external aspect of the phragmocone of B.paxillosus is given in the next diagram, 

 in three aspects, dorsal, lateral, and ventral. The figures are restored, from a variety of 

 specimens which give the requisite information, no one being complete. 



DIAGRAM 7. 



Dorsal aspect. Lateral aspect. Ventral aspect. 



The surface of the conotheca is marked by lines of growth in singular and charac- 

 teristic curves, first accurately examined by Voltz. 1 According to tins observer, the 

 conical surface may be described in four principal regions radiating from the apex ; one 

 dorsal, with loop lines of growth advancing forward ; two lateral, separated from the 

 dorsal by a continuous straight or nearly straight line, and covered with very obliquely 

 arched lines in a hyperbolic form, in part nearly parallel to the dorso-lateral boundary-line, 

 and in part reflexed, so as to form lines in retiring curves across the ventral portion, nearly 



1 ' Observations sur les Belemnites,' 1830. 



