Stewart.] Cretaceous Fishes. 301 



The maxilla of this species is very similar in general form to 

 that of 7. hamatus, with the exception of being less slender and 

 more robust. So far as can be seen, the superior border is 

 nearly straight and much thickened, with a groove along the 

 external side for the reception of the jugal. This border rounds 

 off regularly into the internal. The condyle for the palatine 

 is similar in form to that of /. hamatus, beneath which the bone 

 is very thick. The anterior condyle is oval in outline and situ- 

 ated quite a distance from the last. The surface for the pre- 

 maxilla is bent inward and is much roughened. The anterior 

 border is very sharp and the lower is separated from the alveolar 

 border by a prominent notch. This last border is very concave 

 in the anterior portion and has a prominent hook-like projection 

 extending downward in front, which is broken away in Professor 

 Hay's specimeu. The teeth are rounded in cross-section and 

 non-striate under the microscope. Both the external and inter- 

 nal surfaces of the bone are finely striated. 



Premaxilla : Greatest depth 50 mm. 



Length of alveolar border 32 " 



Maxilla : Depth at posterior condyle 31 " 



Distance between superior condyles 21 " 



Number of alveoli in one centimeter 3 



Fragments of the dentaries show these parts to be remarkably 

 thickened at the symphysis. At this point the alveolar border 

 is directed slightly upward, forming a slight hook-like pro- 

 jection, below which the symphysis descends almost vertically. 



Dentary : Greatest lateral width at symphysis 11 mm. 



Number of teeth in one centimeter 3 



This specimen, No. 180, was obtained from the Niobrara 

 Cretaceous of (love county by Mr. E. P. West some years ago. 



Ichthyodectes acanthicus ?. Plate LI, figs. 1-11. 



Ichthyodectes acanthicus Cope, Proc. Am. Phil. Soc. 1878, p. 177. 



This species, as described by Professor Cope, is the smallest 

 member of the genus, but the description, as a whole, is so very 

 meager that the species cannot be identified with any degree of 

 certainty. There are two specimens in our collection which are 

 much smaller than any of the other species described by Cope, 



