298 University Geological Survey of Kansas. 



Ichtliyodectes hamatus. Plate XLVII, fig. 2; plate L, figs. 1-7. 

 Ichthyodectes hamatus Cope, Proc. Am. Phil. Soc. 1872, p. 340. 



This species is represented by a fragmentary skull and ante- 

 rior vertebrae of one individual and a portion of a dentary and 

 a hyomandibular of another. 



The maxilla is a long, slender bone, which is thickened 

 along the superior border and rather thin along the inferior. 

 The alveolar border is remarkable for the way in which it is 

 directed downward anteriorly just back of the premaxilla. This 

 border is concave from before backward, and supports alveoli 

 for nearly fifty teeth, about half of which are functional at once. 

 The surface for the premaxilla is directed inward and is coarsely 

 striated. It is similar in many respects to I. cruentus, and the 

 premaxilla was no doubt directed downward as in this species. 

 The posterior superior condyle is irregular in outline, and has 

 its internal portion continued downward on the inner side. 

 The anterior condyle is rather small, directed inward, and sepa- 

 rated from the posterior condyle by a long, smooth space. In 

 front of this the anterior border descends almost vertically. 

 The posterior extremity is expanded and directed slightly 

 upward. The external surface is finely striated above, and 

 covered with small pits just above the alveolar border. Un- 

 fortunately the premaxilla is not present. 



Maxilla : Length of alveolar border. 117 mm. 



Depth of posterior condyle 30 " 



Distance between superior condyles 20 " 



Number of alveolas in one centimeter 4 



The condyle of the quadrate is elliptical in outline, and is not 

 projected forward as much as in I. ctenodon. The groove for 

 the symplectic is broad, and reaches downward to within 22 

 mm. of the condyle, below and back of which the bone is much 

 thickened. 



Only the upper portion of the dentary is preserved, which 

 shows this part to be thicker in cross-section than in I. anaides. 

 The anterior extremity of the alveolar border is produced up- 

 ward into a hook-like process, from which character the species 

 probably derives its name. This portion bears two teeth and is 



