596 PROF. H. G. SEELEY ON THE DINOSAURIA OF 
This specimen may be referred provisionally to Prof Huxley’s 
genus Acanthopholis, though there is no certain evidence of its 
generic determination ; its occurrence would justify the anticipation 
that this type of axis will be found to characterize all Cretaceous 
Dinosaurs. It is, however, remarkable that in Zanclodon the rela- 
tions of the axis and the centrum of the atlas are entirely Croco- 
dilian, and that the forms of the bones are so absolutely similar to 
the same elements in a Crocodile as to add a new element to the 
affinities of the Dinosauria, as indicated by this portion of the verte- 
bral column. 
Parr Il. 
On the Vertebral Characters of Acanthopholis horridus, Hualey ; 
from the base of the Chalk Marl near Folkestone (figs. 2 & 3). 
Prof. Huxley’s account of the remarkable Cretaceous Dinosaur 
named Acanthopholis* is the basis for all future comparisons in 
estimating the affinities of the allied types which I am about to 
describe, some of which belong to species of the same genus, and 
others to genera all more or less nearly related. The most striking 
of the remains from the Cambridge Greensand are often portions 
of vertebral columns; and as the vertebree of Acanthopholis have 
not hitherto been figured, it becomes necessary to add to the original 
description of the genus some account of these remains, part of 
which are in the Museum of the Geological Survey, while others are 
in the British Museum. As these remains were found at the same 
time they probably belong to one individual. Altogether there are 
hardly more than six or eight vertebrae, which give characters of 
the dorsal and early and later caudal portions of the series. 
Dorsal Vertebrw.—The dorsal vertebra of Acanthopholis was briefly 
described by Prof. Huxley (Geol. Mag. 1867, vol. iv. p. 66). It 
is preserved in the Museum of the Geological Survey. 
The anterior articular end of the centrum is 2 inches deep from 
the neural canal to the base, is vertically ovate in outline, 1,8, inch 
wide in the middle, and 1,4, inch wide at the upper part below the 
pedicels for the neural arch. The margin of the centrum is im- 
perfectly preserved, and the flattened face is slightly concave. 
The length of the centrum is 2,1, inches. The sides and base of 
the centrum are rounded from above downward. There is a very 
faint median ridge at the base, making the bone less concaye from 
front to back than at the sides. The width of the middle of the 
centrum from side to side is 1,%, inch, and the width at the base of 
the neural arch in the middle of the centrum is 1,4, inch ; the depth 
from the base of the neural canal to the base of the centrum is 1,5 
inch. The neural canal is narrow with parallel sides; in front it 
is =, inch wide, and causes the centrum to project slightly below it 
anteriorly. The canal is deeply excavated in the bone. The con- 
dition of preservation of the specimen gives no indication of a suture 
with the neural arch, which probably existed. 
* Geol. Mag. 1867, vol. iv. p. 65, 
