452 GEOLOGICAL SUEVEY OF THE TEREITOEIES. 



yet determined. The portion of tibia is from the base of the cnemial 

 crest, so that one extremity is trilobate, the other transverse oval. 

 The former outline indicates two posterior tuberosities. The bone is 

 solid, and the superficial layer, for three millimeters or less, is so dense 

 and glistening as to resemble cementum. Portions referred to fibulse 

 have a subcrescentic section, with narrowed width in one direction. 

 Two fragments of shafts of long bones 1 cannot determine either as be- 

 longing to the limbs or pelvis. They belong to opposite sides ; each is 

 oval in section, and the diameter regularly contracts to one end. One 

 side is slightly convex in both directions ; the other is less convex trans- 

 versely, and gently convex longitudinally. A peculiarity consists of a 

 central cavity present in both at the fractured large end, which is bord- 

 ered by a layer of dense bone like the outside. 



Measurements. 



M. 



Transverse diameter of tibia fragment below cnemial crest 125 



Autero-posterior diameter of tibia fragment at base of crest 095 



Width of fragment of fibula 073 



Thickness of fragment of fibula 035 



Length of fragment of unknown bone ' .145 



Proximal diameter of unknown bone 088 



Distal diameter of unknown bone 065 



The above measurements indicate a larger animal than the Cionodon 

 arctatiis, and one not very different in size from the Lcelaps aquilunguis. 



CEOCODILIA. 



BOTTOSAUEUS, Agass. 



Cope, Proceed. Amer. Philos. Soc, 1871, 48. 

 BOTTOSAuilUS PEEEUGOSUS, Sp. nov. 



Eepresented by numerous fragments, with vertebrse and portions of 

 skull which accompanied the dinosaurian and turtle remains from East- 

 ern Colorado, already alluded to. 



A portion of the left dentary bone containing alveoli for ten teeth 

 shows that this sjiecies is not a gavial. The dental series passes in a 

 curve from the inner to the outer sides of the bones, one or two alveoli 

 behind being probably bounded on the inner side by the splenial only, 

 as in B. macrorhynchus, w^hen that bone is in place. The dentary is 

 compressed at this point ; in front it is depressed. There is a slight dif- 

 ference in the sizes of the alveoli, but not such as is usual in Tertiary 

 crocodiles. The external face of the bone exhibits deep pits in longitu- 

 dinal lines. The angle of the mandible is depressed ; the cotylus of 

 articulation is partially concealed on the outer side by the elevation of 

 the surangular, whose upper border is parallel with the inferior margin 

 of the ramus for two inches to where it is broken off. The outer face 

 of this region is marked by irregular coarse ridges more or less inoscu- 

 lating, separated by deep pits. The lower posterior half of the angular, 

 bone is smooth. 



A posterior dorsal or lumbar vertebra has a depressed cordate articu- 

 lar cup. The zygapophyses are large and widely spread, and strength- 

 ened by obtuse ridges running from the base of the neural spine to the 

 posterior margin of the anterior and the posterior outer angle of the 

 posterior. One pit at basis of neural spine in front ; two before. Ball 

 prominent ; sides of centrum concave. 



