CROCODILIA. 155 



and is narrower than the C. elliottii and C. affinis. It belongs with the latter 

 in the group with robust frontal bone with strong lateral ridges. 



The top of the muzzle is absolutely flat, transversely and longitudinally. 

 In this respect it differs from the C. americanus, which is characterized by 

 the presence of a strong convexity of the posterior part of the nasal bones, 

 and the parts adjoining. The table of the skull is wider than long ; the 

 orbits are convex inwards but not regularly, so that the outline of the inter- 

 orbital part of the frontal bone contracts forwards. Anteriorly the orbits 

 are angulate by the union of two oblique borders, the malar and prefrontal. 

 The angle which is in the lachrymal bone, is continued as a shallow gutter 

 for a short distance forwards. There are no crests on the head. The 

 anterior extremities of the nasal bones are prolonged a short distance into 

 the external nares. The jDostero-external angle of the squamosal bone is 

 compressed. The undulation of the superior alveolar line is moderate, 

 The external edge of the pterygoid bone is thickened and truncate. 



A considerable triangular area of the supraoccipital bone appears on 

 the superior face of the skull. The premaxillary bone measured to its 

 posterior apex, enters the length to the extremity of the quadrate bone, 

 three and two-thirds times, or a little more than three times, to the posterior 

 border of the cranial table. The palatine bones extend very little beyond 

 the anterior boi'der of the inferior orbital openings, a character in which the 

 O. acer resembles the C. affinis, and differs from the C. americanus* 



The pitting of the surface of the skull is strongly marked everywhere, 

 except on a very small space at the junction of the frontal and nasal bones. 

 Five pits may be counted across the middle of the interorbital front of the 

 frontal bone. On this bone they are subround and not deep nor confluent, 

 but are separated by ridges narrower than themselves. 



There are five premaxillary and thirteen maxillary teeth on each side. 

 They present characters which readily distinguish them from those of any 

 other species known to me. Their sizes are graduated, and the larger ones 

 do not present an abrupt contrast of size, as in C. jiolyodon. Their 

 ci'owns are all more or less compressed, and have distinct acute cutting 

 edges. The compression is most marked on the last six of the maxillary 



* For fine specimens of this species I am indebted to the Smithsonian Institution at Washington. 



