612 GEOLOGY OF OHIO. 



The largest of these teeth is almost four inches lon& and bluntly 

 conical, and was set in the alveolus of the jaw as shown. This structure 

 is not common among fishes where the teeth are either attached to the 

 skin as in the shark, etc., or are anchylosed to the mandible as in most 

 of the Teleosts. Examples are not, however, wanting of their insertion 

 in an alveolus or even in distinct bony sockets as in Pristis, Sargodon, etc. 



Though we actually know the teeth of T. Clarki only, yet it is 

 scarcely rash to infer that the other species were similarly furnished. 



The only parts previously described of Titanichthys were as follows: 



Titanichthys Clarki; Mandibles, Ventral? plate, Suborbital, Supra- 

 scapula and Coracoid with a tooth marked doubtful. (Monograph, New- 

 berry.) 



T. Agassizi; Mandibles, Cranium, Suborbital, Exoccipital (part.) 

 (Monograph, Newberry.) 



We have at present no means of determining to which species the 

 clavicles? here figured belong as no part of the head was found with any 

 of the specimens. 



Regarding the habits of the genus we can do little more than specu- 

 late. A glance at the mandibles represented on Plate V is sufficient to 

 show that they cannot have been tyrants of the ocean as were the Din- 

 ichthyids. Jaws so long and slender were ill-adapted for- tearing and 

 fighting. They lacked the bony strength and motive muscles of Dinich- 

 thys. Yet the teeth were formidable to creatures less heavily armoured. 

 The size of the mouth, 3 by 4 feet when open, enabled Titanichthys to 

 take in fishes of no small size which were most likely swallowed whole 

 or but slightly crushed. But the thinness of the plates of the head ren- 

 dered it far inferior to Dinkhthys as a warrior. 



The suggestion has even been made that. Titanichthys was a vegeta- 

 rian and used his long jaws and their teeth for collecting sea-weed. Such 

 a mode of life is possible but far from probable. Few fishes, so far as 

 we know, live on sea-weed and very few large fishes are not carnivorous. 

 Some day the coprolites will be found and will solve the problem. 



Titanichthys attenuatus, Wright, sp. nov. 



( Plate 42, Kigs. 1, 2.) 



Mand'.ble, slenderer and lighter than in the two species of the genus, 

 described by Dr. Newberry, the anterior portion running out into a thin, 



Note. To state more minutely and exactly the evidence on this somewhat 

 critical point we will give the details of this find : The base of a tooth was found 

 set in the alveolus but the tip was missing. About three inches from this spot the 

 second tooth was found broken into two pieces. One of these, the base was in the 

 same slab with the jaw. The other was in the adjoining stone so that the parts 

 were only separated by a natural joint. 



The attachment of the teeth to the mandible was not apparently very close, and 

 certainly there was no bony union as this is the only specimen yet found showing 

 teeth that can confidently be referred to the genus. 



