394. G. C. Crick—Actinocamaz from the English Ohaik. 
saw-like cuts. As these marks are not quite at the extremity of the 
specimen, the guard does not appear to have been bitten through, but 
rather to have broken off short during the Belemnite’s struggles to 
escape. That the animal did not long survive the injury seems 
evident from the fact that the edges of the fractured surface are still 
fairly sharp; had the creature lived long after the guard was fractured 
these edges would doubtless have been more or less rounded off by the 
more or less enveloping mantle. 
Measurements. 
mm. 
Length ids F 70+ 
Dorso-ventral diameter at the most inflated part 12 
Transverse diameter at ditto a oe loRo me 
Dorso-ventral diameter near anterior end Saal tlt oe 
Transverse diameter near ditto ... she 10°35 
Affinities and differences.—In a dorsal aspect the specimen agrees 
fairly well with M. Janet’s figure (fig. 5) of the dorsal surface of 
Actinocamax Alfridi,' but in a lateral aspect the dorsal and ventral 
surfaces are much more nearly parallel than are indicated in that 
author’s fig. 5c. Again, the transverse section at the most inflated 
part of the guard is markedly depressed and not so nearly circular 
as in Actinocamax Alfridi. The depressed form of the transverse 
section of the posterior part of the guard agrees more closely with 
M. Janet’s figures of <Actinocamax Grossowvrei,* but the guard in 
that species is not so lanceolate, and has its anterior end depressed 
instead of compressed; further, in a lateral aspect its alveolar end 
tapers much more rapidly than that of the present specimen. Like 
the form described above, the present specimen seems to be inter- 
mediate between <Actinocamax Alfridi and A. Grossouvrer; and it 
also is not identical with any described form of the genus known 
to the present writer. Compared with Actinocamax Blackmorer 
described above, the present example exhibits several differences, 
which may or may not prove to be of importance. The specimen 
is more slender, and when viewed ventrally is relatively less 
inflated at its broadest part; its ventral surface is flatter; the 
transverse section at its broadest part is relatively more depressed ; 
and, in a lateral view, this specimen tapers evenly and slowly from 
the anterior end backwards, whilst in the same aspect A. Blackmorei 
is a little inflated at about the middle of the guard. Owing to its 
imperfection the writer, however, has not ventured to name this fossil. 
Horizon and locality.—This specimen was obtained by Mr. G. E. 
Dibley, F.G.S., from the Mveraster cor-anguinum zone of the Chalk 
in Messrs. Fletcher & Co.’s pit at Gravesend. It is the specimen 
which, in his paper ‘‘On the Zonal Features of the Chalk-pits in 
the Rochester, Gravesend, and Croydon Areas,” Mr. Dibley records * 
from this pit as Actinocamax, n.sp.; amongst other fossils recorded 
from the same pit being Actcnocamax verus and Actinocamax Merceyr 
1 Bull. Soc. géol. France, sér. 111, tom. xix, No. 9 (Nov., 1891), pp. 720, 721, 
pl. xiv, fig. 5, and text-fig. 4. 
2 Ibid., pp. 716-719, pl. xiv, figs. 1-3, and text-figs. 2, 3. 
> Proc. Geol. Assoc., vol. xvi, pt. 9 (August, 1900), p. 495. 
