2G6 PROCEEDINGS OF THE ACADEMY OF 



Char, specif. The pitting of the maxillary bone is not linear, 

 and is sometimes round ; it is rather remote. The outside of the 

 bone is steep, indicating that the muzzle is not depressed. Its 

 face is swollen opposite the supposed canine tooth. The alveolae 

 are round, and longitudinally oval. The alveolar face is decurved 

 near the end of the muzzle. The superficial layer of the cranial 

 and dermal bones is dense and fine grained. The second series 

 of specimens, whose reference is by no means certain, but which 

 contains a dermal bone like that of the type, includes fragments 

 apparently of the upper surface of the cranium. This is marked 

 with irregular tuberosities and excavations resembling that seen 

 in the Belodonts of the Carolinian and Wiirtembergian Trias. A 

 section of a narrow dermal bone displays an elevated obtuse me- 

 dian keel, the only bone which displays this form in the collection, 

 the usual form being either flat or slightly concave. Accompany- 

 ing the same, are numerous coprolites, which are apparently too 

 small' for an animal of the dimensions of the type specimen. They 

 are slender, and display rectal folds, which do not exhibit a con- 

 tinuous spiral. They are found, wherever fractured, to be filled 

 with the rhomboganoid scales of some small fish. 



Measurements. M. 



Length of fragment of maxillary 095 



Depth (oblique) at ? nostril 050 



Depth (vertical) " 045 



Width (median) " 025 



Width at front alveolus 035 



Diameter canine alveolus 015 



Diameter of another alveolus 011 



Diameter centrum (? caudal) vertebra j JJJgJJJ] 6 ' "022 



Thickness of dermal shield 008 



Measurement across four fossa? of do 020 



Diameter of crown of tooth No. 2 018 



Length of coprolite of No. 2 045 



Diameter " 011 



The flat and regularly pitted dermal bones distinguish this genus 

 from Belodon. The species was of large size, the cranial fragments 

 equalling corresponding portions of the Gangetic gavial. 



The evidence derived from the Typothorax coccinarum is favor- 

 able to the identification of this horizon with that of the Trias, 

 although it cannot of course be regarded as conclusive, until more 

 perfect specimens are obtained. 



Besides the overlying sandstone bed, the red marls are traversed 

 below it by a conglomerate, which is in some places of a bluish 

 tint. At some points it weathers to gravel, and near this horizon 

 the vertebrate remains occur. 



In review I give the following section of the Eocene rocks* of 

 the region west of the Sierra Madre range : 



