328 M. S. Lull — Mammals and Horned Dinosaurs. 



thew says of the latter, it is not very clear whether the faunal 

 difference is due to diverse local environments, or to a great 

 movement of faunal migration, but a combination of both 

 seems to fit the data more exactly. This would indicate that 

 the apparent absence from the Lance of the more primitive 

 and archaic groups of the Puerco-Torrejon fauna may be a 

 matter of environment; but that the absence of the larger, 

 more progressive and abundant Palseocene placentals from the 

 Lance is to be ascribed to a migration movement after its close. 

 The evidence on this point is, however, too scanty to be of any 

 considerable weight. 



Reconnaissance of 1914 



The writer's visit to the Lance beds last summer was far too 

 brief to be of material value, but it stimulated the gathering 

 of data as a basis for future work. The difficulty of securing 

 exact information regarding the old collections has proved 

 well-nigh insuperable, for the field records are very meager, 

 and of those who collected the mammals in the Yale Museum, 

 but one, Mr. Peterson, then at the beginning of his valued 

 career as a practical paleontologist, is available for further 

 information. Such as he has I have been able to utilize in 

 full. 



Our party entered Wyoming from Sioux County, Nebraska, 

 following the course of Indian Creek nearly to its source, then 

 over the divide to Sage Creek, missing the Hat Creek post- 

 office and Hatcher's old trail by turning north on the mail 

 road to Warren instead. Hence we entered the Ceratopsia 

 region from the east, making our camp on the Johnson Brothers' 

 ranch at the point where their original dugout cabin lay, in a 

 small tributary canyon which entered that of Buck Creek from 

 the east and a mile or more from the confluence. Mr. Done- 

 ghy, who accompanied me, took up the task of running a sec- 

 tion from Buck Creek west toward Lance, while I spent the 

 time in exploration, trying by means of Hatcher's map to 

 locate both geographically and stratigraphically the more 

 important ceratopsian and mammalian localities. The map 

 proved to be very sketchy, and the exact identification of locali- 

 ties worked twenty or more years before in a complex of 

 topographic features was a matter of extreme difficulty. 



Several of the larger counties of Wyoming have lately been 

 divided into two or more portions, including the old county of 

 Converse. Here the division runs north and south, a little 

 east of the mid-line. The name Converse is still retained for 

 the somewhat larger western part, while the Niobrara River 

 which rises in the eastern portion has given its name to the 

 remainder. It so happens that the entire area of the " Con- 

 verse County beds," which were embraced by the old political 



