Cope.] '^J-*^ [April 15, 



one as large as the gavial of India, the other smaller. In the former the 

 muzzle is keeled above, and rises into a crest in front of the nares. In the 

 other species the muzzle is subcylindric, and does not rise anterior to the 

 septum of the nostrils. The larger species I call Belodon buceros ; the 

 smaller one B. scolojxix, and define them below. Bones of the skeleton 

 and of the dermal systems of this genus are common in the New Mexican 

 beds, but I am yet unable to refer them positively to the species repre- 

 sented by the skulls. 



C7iar. Specif. Size of the gavial. Muzzle slender, compressed, with a 

 narrow median superior ridge, rising at the middle of the length into a 

 compressed crest, whose summit is in the plane of the frontal region. 

 Nostrils a little further anterior to the orbits than the diameter of the lat- 

 ter, longer than wide, and separated by a thin septum. Orbits round, 

 looking a little upwards, the interorbital region a little narrower than 

 each orbit. Preorbital region compressed ; preorbital foramen large, in- 

 ferior. The quadrate bones are directed forwards, and then downwards, 

 and tlieir articular faces are in the transverse line of the two rather narrow 

 notches of the posterior outline of the parietal bone. The auricular meatus 

 is bounded posteriorly by a descending hook-like process ; and the 

 squamosal bone is continued still further posteriorly into a short triangular 

 acute horn. The superior surface of this bone, with the parietal and 

 frontal, are roughened with tubercles. The palate has a strong ridge 

 on each side, so as to be grooved. The posterior teeth have compressed 

 denticulate crowns. Tip of muzzle lost. Total length preserved, M. .700; 

 length of muzzle to posterior edge of nares, .420 ; do. from latter to lines 

 of anterior edge of orbits, .060 ; do. from do. to posterior parietal notch, 

 .160. Width at posterior border of quadrate condyles, .260 ; interorbital 

 do., .048 ; do. at slender part of muzzle, .045. Depth of slender part of 

 muzzle, .050 ; do. of elevated part, .120 ; do. at parietal region, .140. 



This species is of the size of the B. kapfl Meyer, and is, in the form of 

 the muzzle, intermediate between that species and the B. plieningeri. 



Foramina. The alisphenoid bones embrace the olfactory lobes of the 

 brain as far forwards as the middle of the orbits, when they contract to a 

 foramen of moderate size. The under face of the median line of the 

 frontal bones is openly grooved in continuation. The basioccipital has a 

 horizontal axis, and is about as long as wide, including the condyle. Its 

 anterior border has a median apex or proj ection on the sphenoid. The latter 

 forms a transverse band of small anteroposterior diameter to a sharp trans- 

 verse truncation or anterior border. Whether this is the boundary of this 

 element or not is uncertain. It is probably merely a transverse crest, 

 since in front of it the basicranial axis is continued. The latter is deeply 

 concave in the middle, but sends downwards a process on each side, which 

 fits into a notch of the posterior internal border of the pterygoids. Between 

 these notches the pterygoids underroof the axis, and unite on the median 

 line. This union has a less anteroposterior extent than is represented by 



