754 J. W. HULKE ON ORNITHOPSIS; 
is my first vertebra (No. 67, Coll. H.), shown to the Society 
February 9, 1870. The spongy tissue, almost restricted to the ends 
and lower part of the centrum, is coarse, but not nearly so large- 
celled as in No. 67. This textural difference may not improbably 
be due to the different ages of the two animals to which the ver- 
tebre belonged. No. 67 was one of the largest, and this centrum 
(No. 178, Coll. H.) is by much the smallest of a score which at the 
present time are known to me. A gradational difference of texture 
capable of simple and natural explanation, and outweighed by very 
close correspondence of figure, does not appear to me to be a sufli- 
cient ground for regarding the smaller centrum as representing a 
new species, and I consider it simply as coming from a much 
younger individual. The absence of rib-joint from the centrum 
places this vertebra in that part of the vertebral column which in 
the crocodile is behind the 12th centrum; and the very large size 
of the lateral openings and of the chambers confirms this position. 
The genus Oriithopsis was founded in 1869, by Mr. H. G. Seeley, 
on two vertebral centra preserved in the British Museum. Both 
originally formed part of the collection of the late G. A. Mantell. 
The first is labelled No. 28362, Wealden, S.E. England. The 
second, No. 2259, Mantell regarded and figured as the tympanic 
bone of Iguanodon, although, as he mentions, he had recognized in 
it some resemblance to a vertebra*. This determination was adopted 
by Prof. R. Owen, who described it as a tympanic bone in his 
** Reports on Brit. Foss. Rept.,” 18417, and again described and 
figured it as such in Pal. Soc. vol. for 1854, with the reservation 
that it might perhaps be the tympanic bone of Ceteosawrus or of 
Str eptospond, ylust. The vertebral nature of this fossil, as has been 
mentioned by Prof. Owen in 1875, in his memoirs on Bothrio- 
spondylus, was first clearly perceived by Prof. H. G. Seeley§. In 
a paper read at the sitting of the Cambridge Philos. Society, No- 
vember 22, 1869, he announced this new view of its skeletal posi- 
tion, sketched the more striking features common to it and to the 
centrum No. 28362, Brit. Mus. Catal., asserted their distinctness 
from all known yertebral forms, drew attention to their likeness 
(in respect of the extreme lightness of their construction and the 
side opening) to the vertebree of Pterodactyles and birds, threw out 
suggestions relative to the habits and affinities which this struc- 
tural resemblance seemed to indicate, and gave to the new genus 
represented by these fossils the generic name Ornithopsis ||. 
A few months after this, my first note, ‘On a new and unde- 
scribed form of Wealden Vertebra,’”’ was read here 4]. It showed the 
former existence in the Wealden district of a huge Saurian, far 
exceeding Mantell’s Iguanodon in bulk, having trunk-vertebree 
* Geol. of 8.E. England, pp. 305, 306, pl. ii. fig. 5, and Fossils of Brit. Mus. 
(8vo, London, 1851), p. 255. 
+ Brit. Assoc, Rept. 1841, vol. xi. p. 124. 
¢ ‘Monogr. Foss. Rept. of Wealden,’ p. 18, pl. x. (Pal. Soe. vol. 1854). 
§ Monogr. Mesozoic Rept. part ii. p. 23, pl. vii. (Pal. Soc. vol. for 1875). 
|| Annals and Mag. of Nat. Hist. 1870, vol. v. p. 279. 
* Quart. Journ, Coot Soe. (1870) vol. xxvi. p. 318, pl. xxii. 
