No. 382.] DINICHTHYID OSTEOLOGY. 761 
is Professor Newberry, who figures it (under the designation of 
“ postmaxillary ’’) in his restoration of D. intermedius’ as if 
suturally united with the suborbital. We have never observed 
traces on the suborbital indicating a connection with a posterior 
element, and as its flat expansion reaches in D. zerrelli almost 
as far as the posterior angle of the head shield, the opercular 
either did not occur in this species, or is represented by the 
hinder part of the suborbital’s expansion. D. intermedius, how- 
ever, had a relatively shorter suborbital than the larger species, 
and theoretically it ought to be followed by a separate plate. 
Newberry’s supposed “ eye capsules,” ? which are preserved in 
a fairly constant position on the visceral side of the skull, we 
interpret as nasal capsules. 
Titanichthys agassizit Newberry. 
The cranium upon which this species is founded is unique, 
and forms one of the principal treasures of the Museum of 
Comparative Zoology. The mandibles belonging to it, how- 
ever, are preserved in the Museum of Columbia University, 
together with all the specimens of T. clarkii that have been 
collected up to within the last few years. 
Newberry describes the head of Titanichthys as being stri- 
angular in outline, over four feet broad at the occiput, the nasal 
portion imperfect in all the specimens known, and the surface 
smooth or granular, marked by incised lines which form a 
pattern indistinctly shown in the specimens yet examined.” 
He made no attempt to describe the osteology in either of his 
species, and the head of T. clarkii was not even figured. The 
“ incised lines ” (sensory canals) are shown after a fashion in 
his representation of T. agassizii,’ and their arrangement is 
still more imperfectly shown in the rough diagrams given by 
Cope + of the same species. Asa matter of fact, the sensory 
canal system is indicated with tolerable clearness on the 
1 Loc. cit. (1889), Pl. LII, Fig. 2. 
2 Ibid., Pl. VII, nen 
3 Ibid., Pl. I, Fig 
t On the AAR of Some Palæozoic Fishes, Proc. U. S. Nat. Museum, vol. 
xiv (1891), Pl. XXXI, Fig. 6 
