120 k. Lydekker—A Wealden Celuroid Dinosaur. 
matic foramen, and a fracture across the centrum of the imperfect 
specimen shows that the inner structure was completely honey- 
combed. The length of the centrum is 1:74 inches. 
Anterior and left lateral aspects of a cervical vertebra of Calamospondylus Foxi ; 
from the Wealden of the Isle of Wight, 3 nat. size; prz. prezygapophysis ; ptz. 
postzygapophysis; 7, rib (restored); f. pneumatic foramen; s. neural spine. 
These features show that the reptile to which these vertebre 
belonged was closely allied to the genus Coluwrus, Marsh;? and it 
remains to indicate in what manner the two forms differ. Now, in 
the American C. fragilis, and also in C. Daviesi? of the English 
Wealden, the cervicals were longer than the present specimen, and 
while the anterior ones were opisthoccelous, the others were amphi- 
ceelous.* Again, the vertebree of Coelurus have the arch placed more 
forwardly on the centrum, so that the prezygapophyses project more 
in advance of the terminal ball of the latter; while the free posterior 
border of the rib is extended backwards to join the postzygapophysis, 
and thus forms a kind of penthouse over the side of the centrum. 
This penthouse seems, moreover, to cause a flattening of the lateral 
and upper surface of the arch, which is quite wanting in the present 
specimens; while the ridge representing the neural spine is much 
more elongated antero-posteriorly in Celurus. 
Other minor differences can be seen by comparing the woodcut 
with the figures given by Prof. Marsh; but the above features are 
sufficient to indicate that the present form cannot be included in 
Celurus, if we use generic terms in the sense in which they have been 
generally accepted in the Theropoda, but that it clearly indicates a 
member of the same family. 
Now, putting aside the specimen on which the genus T’hecospon- 
dylus was based as being too imperfect to admit at present of any 
interpretation of its affinity ;* the only other genus which appears 
to have been hitherto referred to the Celuride is Tanystropheus of 
the Trias, which Prof. Cope considers to be allied to Celurus. In 
the absence of figures of the American forms referred by Prof. Cope 
to Tanystropheus, an exact comparison cannot be instituted between 
1 Amer. Journ, Sci. ser. 3, vol. xxi, p. 341, pl. x. (1881). 
2 See Lydekker, Cat. Foss. Rept. and Amphib Brit. Mus, pt. i. p. 156 (1888). 
3 In the definition of the Celuride on p. 155 of the work last cited, the words in 
anterior region are omitted before the word opisthoccelous. 
4 Prof. Seeley has proposed to refer Cel/urus Daviesi to this genus. 
