Sa MI i i a i a i ie 
145 
Ctenacanthus, a Spine of Hybodus. 
By W. J. Barxas, M.R.C.8S.E.; L.R.C.P.L. 
[Read before the Royal Society of N.S.W.,3 October, 1877.] 
Cladodus, with engravings of teeth of Hybodus and Cladodus 
from the works of Agassiz, Newbery and Werthen. This 
comparison of the external characters of the 
above-named fishes showed, as I think, most conclusively that 
a having teeth similar to those of th 
om the structure of the teeth which I eonsider to per- 
tain to Hybodus (Cladodus ?) belonging to the Coal Measures. 
My investigations, therefore, led me to the conclusion that most 
of the teeth found in the true Coal Measures which had been 
named Cladodus did not belong to that genus at all, but to the 
— Hybodus ; the remainder, comparatively few in number, 
y true i; also Coal Measure 
Hybodi and Cladodi teeth possessed similar structures, just as 
the Hybodi teeth from the Wealden resembled the tet teeth 
7 ag ag bear oo. When I u lished my researches 
of Hybodus in pero Coal Measuves, tat since then I hee 
ascertained that Giebel, in his “ Fauna der Worwele describes in 
