7S 



BRITISH BELEMXITES. 



approaching the ventral side at its origin, and then bending toward the back and 

 becoming subcentral. Phragraocone depressed, inclined toward the ventral side. The 

 three varieties are — 



"\'ar. A. B. compressits, Blain\dlle, pi. ii, fig. 9 (Sand below Inferior Oolite). 

 ,, B. B. compressns, Yoltz, pi. v, fig. 2 (Upper Lias). 

 „ c. B. compressus, Yoltz, pi. v, fig. 1 (Upper Lias). 



The varieties b and c are fully described. The former has a perfectly conical sheath, 

 much striated at the point, the striae continuing on the shell nearly as long as the 

 grooves, viz. for half the length of the apicial region. In the latter variety tlie sheath is 

 conoidal, and the striae are described as plaits about ten in number. The phragmocone 

 in var. b is straight, the sides meeting at an angle of 26°; in c it is a little arched, and 

 the sides meet at an angle of 29°. Yentral furrows were not observed in any of the 

 specimens, which, except in this particular, appear very similar to examples from the 

 Upper Lias of Yorkshire. 



Quenstedt (1848) has treated this perplexing subject with attention. He employs the 

 title of B. comprcsms for the fossils described by Yoltz, from which he separates those 

 of BlainvUle, and uses such compound terms as B. compressus gigas, B. compressm 

 pavillosm, and B. com/rressus co/iicus, for allied forms of the same natural group. 



We have in the English Lower Oolites and Upper Lias plenty of examples of 

 this group of " compressed Belemnites," l)ut they have not been strictly studied and 

 compared. 



Mr. James de Carle Sowerby, in 1829, represented the fossils from the Oolite of 

 AVhite Xab, near Scarborough (' Min. Conch.,' pi. 590, fig. 4), under the name of 

 B. compressus of BlainvUle. Professor Morris, in his ' Catalogue of British Fossils' 

 (1854), refers the same specimens to B. giganteus of Schlotheim. Since that date 

 D'Orbigny (1860) has collected under the same title B. elHpticus of Miller, B. com- 

 pressus of Sowerby, B. qv.inquesulcatus and gigas of Blainville, B. gladius of 

 Deshaves, B. Aale.nsis and longns of Yoltz, B. grandis and aciminafiis of Schubler, 

 B. bipartitus and canaliculatus, of Hartmann ; but this is not a method to be recom- 

 mended. This is not a species, but a group of species, whose geological range includes 

 the Upper Lias and the Lower Oolite. 



Under B. compressus of Blainville D'Orbigny ranged also B. apicicurmtus and 

 B. bicanalicvlatus of that author, B. crassvs of Yoltz, and B. bisulcatus and B. tnmidus of 

 Zieten. 



It appears to me that three distinct British forms may be well marked among the 

 varieties of Belemnites properly referred to B. compressus of Blainville and Yoltz; one is 

 described by the first author ; another includes the varieties b and c of Yoltz ; the third 

 is now illustrated from Yorkshire specimens. 



