2 BULLETIN 169, UNITED STATES NATIONAL MUSEUM 



this same field is also mentioned or discussed. In a few cases classi- 

 fication has demanded some detail concerning fossils from other col- 

 lections and areas, especially the San Juan Basin, in New Mexico, 

 notably in deahng with the genera Claenodon and Anisonchus. 



Most of the new genera and species recognized in the course of 

 this work were named, with brief diagnoses, in a preUminary note 

 abstracted from the first draft of part 2 (Simpson, 1935d). These 

 diagnoses are here repeated, in some cases in emended form, and ac- 

 companied by the extended discussion and description omitted in the 

 preliminary paper. There is included a full discussion of the fossil 

 Primates, even though these have already been published in some 

 detail (Gidley, 1923). 



In the course of preparation of tliis bulletin, I have had access 

 to and have made constant use of a memoir on the Paleocene of the 

 San Juan Basin by the late Dr. W. D. Matthew. This has now 

 been published by the American Philosophical Society, but it was 

 available only in manuscript throughout the course of my work. 

 Reference to it is made by the citation "(Pale. Mem.)." Other 

 citations are by author and year and refer to the "Literature cited" 

 at the end. As far as possible without destroying the comprehensive 

 and unified character of this work, I have avoided any duplication 

 of material contained in Matthew's memoir. For groups that he 

 also discusses I have generally omitted diagnoses and have confined 

 discussion to a brief surmnary and to those pomts wherein I differ 

 from him. 



Throughout this work, wherever they proved useful, statistical 

 methods have been employed. These are all summed up in Fisher 

 (1925) and also in a paper soon to be published (Simpson and Roe). 

 The methodology is outlined here in connection with the first group 

 treated, the Multituberculata. In all the statistical figures given, 

 the stated error is standard, not probable. The following abbrevi- 

 ations are consistently used throughout for brevity, along with the 

 universally understood symbols for teeth. 



L«= Length. 

 W = Width. 



N = Number of specimens in a given sample. 

 R^ Range. 

 M = Mean. 

 o-^ Standard deviation. 

 d/<r== Deviation from a specified mean, divided by the corresponding stand- 

 ard deviation. 



V>=CoeflBcient of variability = --—-• 



M 



P= Probability. Mas defined 



t = A constant for comparing small samples] [by Fisher. 



2(d')'=Sura of the squares of deviations from the mean. 



