BELEMNITES OF THE OXFORD CLAY. 



Belemnites obeliscus, n. s. PI. XXXITI, fig. S3. 



Guard. Very long, almost uniformly tapering to a point, compressed, smooth, or with 

 traces of longitudinal interrupted undidations. In some specimens a defined lateral 

 flattening (PI. XXXIII, /', l^). No distinct apici-ventral groove. 



Greatest length observed 9^^ inch ; greatest diameter in this specimen, just before 

 the conical expansion, less than ' an inch. In shorter specimens, 65 inches long, the 

 corresponding diameter is nearly the same ; in still smaller examples, 31 inches long, the 

 diameter is 5 of an inch. It seems as if two varieties exist, one much longer in propoi- 

 tion than the other. 



Proportions. The normal diameter at the alveolar apex being taken at 100, the trans- 

 verse diameter is 84 ; the axis in the longer variety 2000 and more, in the shorter 1500 

 The excentricity of the axis appears to be very small. 



PuRAGMOCONE. I have only been able to observe the cross section, which is less 

 elliptical than the sectional outline of the guard, the guard-fibres being longer on the 

 back and front than on the sides. In this the fossil is analogous to some Liassic forms. 



Locality. Eathie Burn and Shandwick, with the last-named species. 



Observations. Not only do the unequal proportions of different specimens suggest the 

 idea of a sexual distinction, but the whole group, compared with B. spicularis, leads to 

 reflections of the same order. The guard is colour-banded, as is that of B. spicularis. 



On a Gkoup of Belemnites allied to Belemnites excentricus op Blainville. 



Lister, in his 'Plistoria Anim. Angliac,' pp. 226-228, has the following description of 

 a Belemnite of this group : — " Titulus xxxi. — Belemnites ni(jer, maximus, basi forata." 

 Among the remarks on this species we find " Perfricatum cornu combustum aut quoddam 

 bitumen olet." " In tota iUa agri Eboracensis regione montosa, qui Blackmore appellatm-, 

 prjEcipue abundant ; item in rivulo juxta Bugtliorp, et alibi reperti sunt." The Black- 

 more fossils belong to B. ahhrcviatus; a large fragment was above three inches in circum- 

 ference. Bugthorp is on the Lias. 



Lhwyd, in the ' Lithophylacium Britannicum,' notices Belemnites of this group, from 

 the vicinity of Oxford, No. 1667: — Belemnites maximus oxyrrliynchus, four inches in 

 girth where largest. Cowley, BuUington, Marsham, Stansford, Garford, the localities 

 mentioned, indicate the species to have been what Miller called B. ahhreviaius. 



Smith, in the ' Stratigraphical System,' p. 50, describes a Belemnite as elongate, rather 

 four-sided, from Wotton Basset and Shippon, in the Coral Rag, p. 43, and another, quite 

 similar, from the Kimmeridge Clay of North Wilts. 



Miller described these forms as B. abbrevialus ; his followers have often assigned that 

 name to a species from the Inferior Oolite. 



