BUFFALO SOCIETY OF NATURAL SCIENCES 5 
animal of predatory habits may be inferred from its elongated 
gape and the massing of the large fins at the posterior portion of 
the trunk. 
Its head occupied about one quarter of its length and its great- 
est depth was contained a little more than five times in its total 
length. Its dorsal, ventral and anal fins were placed rather far 
back, the ventrals being located about midway between the first 
and second dorsals, and the anal fin somewhat behind the second 
dorsal. 
A single, enlarged ridge scale occurs immediately behind each 
of the dorsal and the anal fins. Watson and Day (1916, p. 25) 
believe that these scales, present in nearly all members of the 
family, have arisen through the disarrangement of the squamation 
due to the reduction in the width of the insertion of the fins, fol- 
lowing the concentration of their endo-skeletal supports. 
The body was covered with rather small cycloidal scales. On 
Plate 16, I have figured a portion of the squamation of Eusthen- 
opteron foordi and below it for comparison, that of Holoptychius 
quebecensis from the same locality. 
The minute structure of the scales of Eusthenopteron does not 
agree with that of the cosmoid scale as defined by Williamson 
(1849 and 1850) and Goodrich (1909, p 214) and said to occur 
only in the Dipnoii and Crossopterygil; neither can it be said to 
be a true ganoid scale. On Plate 18, figs. 1 and 2, I have figured 
magnified sections; on Plate 17, fig. 1, one of the ornamental 
tubercules more highly magnified; and for comparison with these, 
on Plate 18, figs. 3 and 4, I give sections of scales of Holoptychius 
quebecensis. None of these sections show the conditions said to 
obtain in either the Crossopterygii or the Dipnoii nor, on the other 
hand, do they seem to resemble typical ganoin scales. 
The scale is formed of three layers of true bone with bone cells 
everywhere present. There is neither any trace of dentine or of 
the modified dentine known as cosmine, nor so far as I can find is 
there any such structure as vitrodentine, enamel or ganoin. There 
