J. W. HULKE ON ORNITHOPSIS. 755 
texturally characterized by great compactness of the cortical bone, 
which occurred chiefly in the form of thin sheets, and by an ex- 
tremely large-celled cancellous tissue. As regards their form, the 
vertebra were distinguished by having superadded to the usual 
zygapophyses a vertical bolt-plate produced downwards from the 
median junction of the postzygapophyses, and a corresponding 
notch with smooth articular sides for its reception between the 
prezygapophyses—an arrangement in principle comparable to 
zygosphene and zygantrum. ‘These are shown in figures | and 4, 
pl. xxii., vol. xxvi. (1870). 
Further, these vertebre bore a double rib-joint; they had a sin- 
gularly complex spinous process, and an unusually developed platform 
in the level of the crown of the arch from which the transverse 
process (diapophysis) jutted boldly upwards and outwards to a con- 
siderable distance, strutted and buttressed by thin sheets of bone, 
between which are large and deep recesses. 
These characters collectively justified me in referring the animal 
represented by this fossil to the order Dinosauria; and the singular 
beauty of the groined entrance of the neural canal suggested the 
name Hucamerotus. 
The close agreement of their bony tissues and plan of construc- 
tion had impressed me with the idea of the identity of my neural 
arch and the Manteilian centrum, No. 28632, the first of the 
two centra on which Seeley’s genus Ornithopsis was founded; but 
at the moment proof of this was wanting. Very shortly afterwards 
the Rev. W. Fox showed me in his collection a mutilated centrum, 
retaining enough of the arch and superstructures to establish beyond 
doubt the identity of Hucamerotus and Ornithopsis, No. 28632 
being regarded as the type of this latter. The identification neces- 
sarily entailed the withdrawal of Hucamerotus as a generic name in 
favour of the prior Ornithopsis; and the latter acquired, in addition 
to its opisthoccelous, large-cancellated, side-chambered trunk-centra, 
the characters derived from the neural arch and processes of 
Eucamerotus. 
On September 28, 1870, I found, in a local collection in the Isle 
of Wight, a trunk-centrum of Ornithopsis which, although both ends 
had been shortened by abrasion, measured 11 inches in length, 
6:5 inches across, and about 9 inches in height, affording additional 
evidence of the immense size of the animal. The external opening 
of the side-chamber was a long oval, of which the height was to the 
length roughly as 1: 2. 
A persevering search along the cliffs through the whole length 
of the Wealden exposure at the west end of the Isle of Wight, by 
the Rev. W. Fox, resulted in the addition of several instructive 
pieces to his collection. My own occasional efforts were rewarded 
by the vertebra exhibited to-night and a large very mutilated 
cervical centrum. 
These new acquisitions, to which Mr. Fox, on his part, kindly 
permits me to refer, show that in some of the trunk-vertebree the 
spinous process is expanded transyersely to the direction of the 
