120 Joshua Laerm and James L. Boone 



Given an unknown specimen with hindfoot and skull lengths of 23.5 

 and 28.7 mm, respectively, and the coefficients of these measurements 

 from Table 3, this equation becomes: 



D = -34.125 + 0.593(23.5) + 0.821(28.7) 



D = 3.377 



In this case, any positive value of D indicates P. gossypinus, and any 

 negative value of D indicates a P. leucopus (Table 2). Thus, this 

 specimen is a P. gossypinus. 



If these two species required more than one axis, D\ and Di 

 would be calculated using discriminant coefficients from Table 3 for 

 external and cranial measurements or Table 4 for skull measurements 

 only. The bivariate coordinate (Di, Di) can be plotted on a 2-dimensional 

 graph (e.g., Fig. 3). 



ACKNOWLEDGMENTS — We appreciate the assistance extended 

 by curatorial staffs of the following museums: Carnegie Museum of 

 Natural History (CMNH), Florida Museum of Natural History (UF), 

 Louisiana State University Museum of Zoology (LSUMZ), Harvard 

 University Museum of Comparative Zoology (MCZ), University of 

 Alabama Museum of Natural History (UAL), University of Georgia 

 Museum of Natural History (UGAMNH), and the United States National 

 Museum (USNM). Two anonymous reviewers offered helpful suggestions 

 on an early draft of the manuscript. 



LITERATURE CITED 

 Blair, W. F., A. P. Blair, P. Brodkorb, F. R. Cagle, and G. A. Moore. 



1968. Vertebrates of the United States. Second edition. McGraw 

 Hill, New York, New York. 



Burnaby, T. P. 1966. Growth invariant discriminant functions and 

 generalized distances. Biometrics 22:96-110. 



Choate, J. R. 1973. Identification and recent distribution of white- 

 footed mice (Peromyscus) in New England. Journal of Mammal- 

 ogy 54:41-49. 



Choate, J. R., R. C. Dowler, and J. E. Krause. 1979. Mensural 

 discrimination between Peromyscus leucopus and P. maniculatus 

 (Rodentia) in Kansas. Southwestern Naturalist 24:249-258. 



DeBlase, A. F., and R. E. Martin. 1981. A manual of mammalogy 

 with keys of the families of the world. Second edition. Wm. 

 Brown Company, Dubuque, Iowa. 



Engstrom, M. D., D. J. Schmidly, and P. K. Fox. 1982. Nongeographic 

 variation and discrimination of species within the Peromyscus leucopus 

 species group (Mammalia: Cricetinae) in eastern Texas. Texas Journal 

 of Science 34:149-162. 



