96 BRITISH BELEMNITES. 
Bel. unisulcatus, Blamville, ‘Mém. sur les Bel.,’ pl. v, fig. 21; D’Orbigny, ‘Ter. 
Jur., pl. vii, figs. 1—4. Bridport and Bradford Abbas. 
I regard these as all truly Liassic forms, to whatever extent they may hereafter be 
found continued into the Oolitic strata. 
BELEMNITES OF THE OOLITIC SYSTEM. 
Regarded from the most general point of view, the Belemnites of the Oolitic lime- 
stones, sands, and clays present themselves in five natural groups, which may be thus 
typified : 
1. Group of Belemnites giganteus, Blainville. Large compressed species, with a nearly 
regular elliptical or oval section ; no ventral groove. 
2. Group of Belemnites canaliculatus, Schlotheim (sw/catus, Miller). More or less 
depressed ; the ventral surface conspicuously grooved in the middle part of the guard. 
3. Group of Belemnites hastatus, Blainville, whose remarkable elongation, hastate 
shape, and deep ventral groove, mark them distinctly. 
4. Group of Belemnites tornatilis, Phillips (Owen, Pratt ; Pusozianus, D’Orbigny). 
Long subcylindrical Belemnites, with a groove on the ventral aspect towards the apex 
of the guard. 
5. Group of Belemanites abbreviatus, Muller (eacentricus, Blainville). Large short 
Long Belemnites, plane or broadly grooved on the sides, flattened or slightly grooved 
near the apex on the ventral aspect. 
I propose to describe these groups in the order set down ; and have only now to 
remark, by way of introduction, that the first group may be regarded as continued from 
the Upper Lias into the Bath Oolite series, where apparently it grows to the utmost 
magnitude, and then ends. ‘The second group begins in the lowest of the Oolites and 
ascends to the Oxford Clay, not, I believe, to the uppermost part of that deposit. The 
third group, notwithstanding its seeming resemblance to Be/emnites clavatus of the Lias, 
is really more allied to the second here noted ; it begins in the Bath Oolite series, but not, 
I believe, at the base of it, and extends into the Kimmeridge Clay. Its relation to 
B. jaculum of the Speeton Clay and B. pistilliformis of the Neocomian beds, and the 
small Belemnites of the Folkestone Gault, will be considered hereafter. The fourth group 
extends from the Kelloway Rock to the Kimmeridge Clay. ‘he fifth begins in the 
Oxford Clay, not, I believe, at the base, and extends upwards into the Kimmeridge Clay 
of Oxfordshire, the Speeton Clay of Yorkshire, and the congeneric bed of Lincolnshire called 
Tealby Stone. 
