tee ee ee ee eee eg aE ee ee, 
ae : ~ 
* 
CTENACANTHUS, A SPINE OF HYBODTS. 153 
tubal ar arrangement pho, on easly of ‘ie hardness 
of ~ fossi lized spine and of the consequent brittleness when the 
b roces 
sec is becoming transparent under the 
ng have now compared the spine of Ctenacanthus with that of 
Hybodus both externally and internally, and e proof is 
most conclusive o their identity, but to some the me 
similarity of form, markin d structure may not be ¢ 
nt evidence to settle this matter. I will therefore for 
“car non n-seulement j je connais les 1 rayons et les dents 
des Higbodes et jai la certitude qu’ils appartiennent au méme 
genre, mais encore j’ai pu m’assurer que partout ow l’on trouve 
des rayons de ce type, il existe aussi des dents analogues et vice 
versa.” Now, in my paper, “ Hybodus, a Coal Measure Fish,” 
I showed that the teeth of Hybodus were found in the Coal 
called spines of Ctenacanthus cannot be disti rng ee from the 
external form or by their minute stru cture. Now the spines of 
Longton, Staffordshire ; it is an undoubted specimen of Ctena- 
eanthus with non-tubereulated ridges, and in close contact with it 
bere 
essrs. Hancock and Seay in a 2 paper which they published 
‘im the “Transactions of the 
umb: 
Natural History Society,” stated their helief that the teeth, 
tubercles and spine, belonged to one‘fish, and Mr. Thompson of 
Glasgow has also given the same opinion, aahnge none am are them 
had seen such a specimen as that in the possession of Mr. Ward. 
