R. 8. Lull — Mammals and Homed Dinosaurs. 347 



much more perfect material than any yet preserved. Possibly 

 more complete jaws or even skulls and associated skeletal 

 remains may be found, which alone will serve to put our 

 knowledge of Lance mammals upon a more exact basis. 



The main conclusions reached in the present paper are as 

 follows : 



1. That the mammals, instead of being confined to any one 

 horizon, are pretty uniformly distributed throughout the 

 entire Ceratopsia-bearing beds. 



2. That the mammals are apt to be not far removed from 

 lignitic deposits and are found in association with often worn 

 scales and teeth of fresh-water fishes, generally in a bone 

 conglomerate at the base of invading sands. This would seem 

 to imply some transportation from the actual living habitat. 

 The associated plant remains, both with the mammals and the 

 Ceratopsia skulls, imply an abundance of vegetation, possibly 

 forested conditions, in their respective homes, whether they 

 differed or not. 



3. That the more conservative and older Multituberculates 

 range throughout the entire Lance, while the Trituberculates 

 thus far found are absent from the lowermost quarries. This 

 seems to be significant, for Multituberculates are known from 

 the Jurassic and become extinct in the JPalseocene, while 

 descendants of the Trituberculates may still exist. 



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