Speciation in the Brazilian Spiny Rats (Genus Proechimys, Family Echimyidae) BY JOÃO MOOJEN University of Kansas Publications Museum of Natural History Volume 1, No. 19, pp. 301-406, 140 figures in text December 10, 1948 University of Kansas LAWRENCE 1948 UNIVERSITY OF KANSAS PUBLICATIONS, MUSEUM OF NATURAL HISTORY Editors: E. Raymond Hall, Chairman, A. Byron Leonard, Edward H. Taylor Volume 1, No. 19, pp. 301-406, 1 plate, 140 figures in text Published December 10, 1948 UNIVERSITY OF KANSAS Lawrence, Kansas PRINTED BY FERD VOILAND, JR., STATE PRINTER TOPEKA, KANSAS 1948 22-3343 Speciation in the Brazilian Spiny Rats (Genus Proechimys, Family Echimyidae) By JOÃO MOOJEN CONTENTS PAGE INTRODUCTION 305 METHODS AND TERMINOLOGY 305 ACKNOWLEDGMENTS 308 PALEONTOLOGY 308 SPECIATION 311 Subgeneric variation 312 Specific variation in the subgenus _Proechimys_ 314 Subspecific variation in the subgenus _Proechimys_ 317 Specific variation in the subgenus _Trinomys_ 320 Subspecific variation in the subgenus _Trinomys_ 322 TAXONOMIC CHARACTERS 323 Size and proportions of external parts 323 Pelage 324 Skull 326 Incisive foramen 326 Teeth 327 HABITS 330 CHANGES WITH AGE 331 Genus PROECHIMYS 333 ARTIFICIAL KEY TO SUBGENERA AND SPECIES 334