No. 382.] DINICHTHYID OSTEOLOGY. 763 
The rostral plate, termed also “nasal” and “ ethmoid”’ by 
different authors, has been entirely broken away from the type 
specimen, together with the forward portions of the preorbital 
plates. The margin of the latter extends for such a distance 
inwardly in advance of the orbits as to suggest that the head 
Fic. 4.— Titanichthys agassizii Newb. Cleveland Shale, Ohio. Diagram showing cranial 
and dorsal shields (partly restored). X jy. Lettering as in Fig. 2. 
was foreshortened in the manner shown by the diagram. It is 
Possible, of course, that both rostral and pineal plates were 
transversely elliptical, instead of the pineal only, as here repre- 
sented ; but in either case the effect on the preorbitals was to 
give them a very different aspect from the usual condition in 
the Coccosteide. These three plates are the only ones which 
differ markedly from their homologues in Dinichthys. 
