THE CAMBRIDGE GREENSAND. 631 
ue is nearly 1,2, inch; the width of the dle face is fully 
7 inch. The last vertebra of the series is ~ inch long. It, too, 
has lost the neural arch, and has the sensu ends more deeply 
excavated and much wider than high. From the relatively small 
size of the base, its outline is subpentagonal. The neural canal 
is very small, and the arch absent from the posterior third. 
In instituting the species on these remains, I rely on the four 
vertebra last described for its type, without in any way doubting 
the natural association of the dorsal vertebree with these caudal ele- 
ments. Still, as three caudal vertebrae of Anoplosaurus had become 
accidentally mixed with them, and the cervical vertebra belongs to 
that genus also, it seems to me unsafe to attribute the dorsal ver- 
tebree unreservedly to Acanthopholis, although we know that that 
region of the body presents no essential difference from the same 
region in Anoplosaurus. As compared with the tail of the type 
species, Acanthopholis horridus, Huxley, this species is distinguished 
by having the middle caudals much more robust, with a deeper basal 
groove and strongly developed facets for the chevron bones, while 
the neural arch is bounded by lateral ridges, which are absent in the 
type species.. The later caudals are relatively more robust than 
in the type, and distinguished by progressively decreasing in length, 
by retaining well-developed chevron facets to the last, and by having 
the neural arch less developed and defined by a deep groove at its 
base. 
Anoplosaurus major. 
The Cervical Vertebra.—I have already suggested the possi- 
bility of this centrum pertaining to a second and larger species 
of Anoplosaurus. The centrum is depressed and broad in front, 
and leans obliquely forward, more so at the posterior than at the 
anterior articular surface. This condition would probably suggest 
that the neck was carried in an upraised. position. The base of 
the centrum is 14 inch long, while the neural canal was somewhat 
less. The base is flattened, apparently with a slight median ridge, 
but is slightly convex from side to side, and the base makes about a 
right angle with the nearly vertical lateral spaces behind the 
articular tubercle for the rib. The vertebra measures from side to 
side 1,1, inch, but the width over the tubercles, as preserved, is 1%, 
inch. ‘The tubercles are on the middle of the side of the centrum, 
close to the anterior articulation, and are about 4 inch in diameter. 
Immediately behind the tubercles the centrum has a pinched aspect. 
The anterior face is transversely ovate, 1 inch deep, as preserved, but 
the underside is a little worn; it is moderately cupped, and was 
about 12 inch wide. The posterior articular surface is somewhat 
deeply cupped, 1,3; inch in depth and 1,3, inch wide. The neural 
canal is very wide, being ;7; inch in diameter. The bases of the 
laminze of the neural arch are compressed, and extend along the 
length of the centrum ; they appear to be confluent with the centrum, 
and show no certain indication of suture. 
Although the caudal vertebra which indicate the second species of 
