R. S. Lull — Mammals and Horned Dinosaurs. 34 L 



Soil and talus 8 



Resistant white concretionary sandstone, a ledge 



maker lto 2 



Hard white massive sandstone, regularly bedded- 15 

 Alternating white to brown sandstone, in beds 



1 inch to 1 foot thick, regularly bedded 10 



Very bard brown sandstone, concretionary, shark 



tooth, about \\ 



Resistant white sandstone l£ ,,„ 



Soil and talus .- 11 



Massive white sandstone 6 to 8 



Soil cover 17 



Massive irregularly bedded buff sandstone 8 



Ceratopsian Localities 



Geologic sequence. — As a result of the labors of Mr. Hatcher 

 and his aids, no fewer than thirty-two ceratopsian skulls in 

 varying degrees of preservation were brought to light, in addi- 

 tion to several partial skeletons. This material was studied in 

 part by Professor Marsh and later, in preparation for the Cera- 

 topsia monograph, by Hatcher and Lull. The collection, there- 

 fore, includes every Lance ceratopsian type and nearly all of 

 the figured material, so that its importance can not be over- 

 estimated. The material is now about equally divided between 

 the United States National Museum and that of Yale. The 

 collection of the former institution is entirely prepared, while 

 upon the Yale material there is still much to be done. The 

 skulls were given a series of numbers, 1-19, and 19A-3L, mak- 

 ing thirty-two all told, while the skeletons were indicated by 

 letter, skeleton C and skull 26 constituting the composite 

 mounted Triceratops at the National Museum. Professor 

 Marsh and Mr. Hatcher naturally chose the best specimens for 

 description, with the exception of the type of Triceratops 

 horridus, which is Skull No. 1, and one or two others. Cir- 

 cumstances were such that the skulls of the upper levels were 

 the best preserved, so that with the exception of skulls Nos. 1 

 and 9 {Triceratops ohtusus), which are the lowest in the series, 

 most of the types come from the upper portion and are all 

 quite near one another stratigraphically, while between No. 1 

 and the next higher known form there are a number of un- 

 identified and indeterminable specimens, which may or may 

 not have their representatives in the higher levels. 



I have arranged the skulls in their stratigraphic sequence, 

 based upon all the data available at present, but taken very 

 largely from a study of the map, and the tables will show not 

 alone the ceratopsian sequence but that of each adjacent 

 mammal quarry as well. I place rather less value upon an 

 evolutionary sequence of ceratopsian species within the Lance 



