Mr. J. S. Miller on Belemnites. 69 



the guard, I must however acknowledge the insufficiency of this part to yield 

 distinctions which may secure us from all error. It is obvious how much a 

 form is liable to be changed where it results from the continual superpositions 

 of fresh laminae^ which if not regularly and conformably secreted, produce not 

 unfrequently considerable deformity and deviations. 



Sp. 1. Belemnites abbreviatus (nobis). PI. VII. fig. 9, 10. 



Sp. Ch. Guard short in proportion to the length of the chambered cone, tapering to 

 a conical and very slightly curved point, compressed on two sides. 



Syn. and Ref. Parkinson's Org. Rem. vol. iii. PI. VIII. fig. 8 & 15. 



Locality, Weymouth, Dundry. 



Stratum. Inferior oolite. 



This species grows large, the chambered cone has generally a lateral po- 

 sition, in consequence of the accumulation of laminae being on one side more 

 than on the other; hence its apex forms frequently a slight curve. The guard 

 is also thicker on one side than the other; hence somewhat suboval, and not 

 unfrequently finely striated longitudinally. 



Sp. 2. Belemnites aduncatus (nobis). PI. VIII. fig. 6, 7, 8. 



Sp. Ch. Guard very smooth yet sometimes finely striated, cylindric, terminating in an 

 aduncated apex marked with four or five ridges, the sulci between which are 

 sometimes slightly tuberculated. 



Locality. Weymouth, Lyme. 



Stratum. Lyas and lyas clay. 



This species is considerably more slender than the former, but otherwise 

 resembles it. 



Sp. 3. Belemnites sulcatus (nobis). PI. VIII. fig. 3, 4, 5. 



Sp. Ch. Guard subcylindrical, elongated, having a longitudinal sulcus, and termi- 

 nating in an acute apex. 

 Syn. and Ref. Plott's Hist, of Oxford, Tab. III. fig. 6. 

 Locality. Dundry, near Oxford. 

 Stratum. Inferior oolite. 



This species has sometimes a considerable thickness, when the sulcus is very 

 distinctly marked, evidently occasioned by the upper laminae not completely 

 surrounding the guard. 



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