FAUNAL EVIDENCE AND COEKELATION. 241 



its equivalent in the Weber grits of the Leadville and Tenmile districts. To the 

 Weber shales belong collections from stations 2250, 2251, 2252, 2253, 22571, 2258, 

 226J:, 2267, and 2277; to the middle Weber those from stations 2262, 2263; to the 

 upper Weber stations 2269, 2272, 2275, and 2276; to the Robinson limestone stations 

 2260, 2261, 2273, and 2274; and to the base of the Maroon formation station 2270. 

 Stations 2251, 2255?, 2259?, 2265, 2266, and 2268 are referred merely to the Weber, 

 and the horizon of 2256 and 2271 was not detinitel}' determined. Of these, all the 

 collections from the Robinson limestone and all but one from the upper Weber are 

 derived from the TenmUe district, from which we ha\-e no collections representing 

 either the lower or the middle Weber. 



Most of this material was studied by R. P. Whitfield, who made the paleonto- 

 logical determinations for the Leadville monograph. It has all been reworked and 

 the identifications brought into harmony with those of the other Colorado collections. 

 1 have agreed with the identifications recorded in the Leadville monograph in some 

 cases, but in others have ventured to depart from them. It would hardlj^ be profit- 

 able, especially since I am in accord with Whitfield's determinations of the ages of 

 the different formations, to make a comparison of the two series of faunal lists fur- 

 ther than this, adding that some of the material appears to have been lost since it 

 was originally studied. In addition to what appear to be losses from the collection, 

 many of the local lots have been thrown together, so that frequentlj- a number of 

 different locality labels were found accompanying a single set of specimens. It was 

 of course impossible to separate these into their original groups, and no attempt was 

 made to do .so. In the following table are included not only the species collected 

 during the field work for the Leadville monograph and Tenmile folio, but also those 

 from two other stations in the same neighborhood, 2281 and 2288, both of which are 

 believed to belong in the Weber shale: 



14361— No. 16—03 16 



