‘Cope.] . 
angles to the alveolar edge to beyond the middle line of the side of the 
maxillary. Above this point a process of the latter extends above the 
premaxillary for half an inch; it has a broad inferior sutural face ; its 
upper margin is thin and oblique. A short truncate process rises behind 
the superior cotyloid surface. The teeth are cylindric conic, slightly in- 
curved; on a margin of .035 M. there are five teeth and five vacant al- 
veoli. The teeth of the inner row are much smaller, and on .017 M., there 
are cight bases. The bases of the two large teeth occupy .014. Depth 
of maxillary at large teeth, .019; at fractured end, .014, The anterior 
teeth of the external series are not larger than those of the inner. 
The precise locality of the Niobrara chalk where this species was found 
has been mislaid. There is a possibility of its belonging to the Pachyrhi- 
zodus latimentum, but the smaller relative size seems to contradict the 
supposition. Should it be verified, the latter species must be referred to 
the genus Hmpo. 
STRATODONTIDA. 
In this group I have arranged several genera which resemble Hnchodus, 
the longest known of its forms. They are Physostomous fishes as indicated 
by the relations of bones of the superior arch of the mouth ; the absence 
of spinous dorsal radii; the cycloid scales, and the general relationship to 
Esoxv. Agassiz and others have regarded some of them as allied to Sphy- 
rend; this opinion was probably derived from the consideration of the 
forms of the teeth which to some degree resemble those of Sphyrenide 
and Trichiuride. This is, however, like many other minor characters, one 
of those which appear in both of the great groups of osseous fishes. 
The premaxillary is small, and supports a large tooth in Hnechodus ; in 
Stratodus it is also short and supports numerous teeth. In Stratodus the 
maxillary supports a few teeth, in Ovmolichthys a larger number. Rela- 
tionship to Hsow is displayed by Stratodus, which has broad flat palatine 
bones closely studded with teeth ina brush, and where the maxillary teeth 
are reduced in size and number. The teeth are attached by the anchy- 
losis of the base to the alveolar face of the jaw, resembling thus existing 
fishes, and differing materially from the families of Pachyrhizodontide 
and Saurodontide already considered, 
he genera known to me are the following : 
Premaxillary with numerous small teeth, maxillary with 
a few of thé same; palatines covered with brushes of 
similar teeth, all with pulp cavity. ........-.e.e eee ree ne Stratodus. 
Premaxillary (?) Maxillary with a single series of large 
teeth which have one cutting edge at base and two at 
apex. Dentary with inner series of large teeth which do 
not enlarge distally, and some series of exterior smaller 
ROBT Lee. 40) orviine. lnenosaua coltalin old. erslQanolichthys- 
Premaxillary with a single large tooth; danitaly with 
an outer row of small and an inner row of large teeth, 
which are much larger at the distal end........-.. 0.060065 Enchodus- 
348 [Jan. 5, 
