F>ROCEEDINGS 



OF THE 



CALIFORNIA ACADEMY OF SCIENCES 



Fourth Series 



Vol. V, No. 5, pp. 111-161, Plate 15 December 30, 1915 



DESCRIPTION OF A NEW SUBGENUS (ABB0EIMV8) 



OF PHENACOMYS, WITH A CONTRIBUTION 



TO KNOWLEDGE OF THE HABITS AND 



DISTRIBUTION OF PHENACOMYS 



L0NGICAUDU8 TRUE 



By Walter P. Taylor, 

 Curator of Mammals, California Museum of Vertebrate Zoology. 



CONTENTS 



Page 



A. INTRODUCTION 113 



B. MATERIAL AND ACKNOWLEDGMENTS 117 



C. ARBORIMUS, A NEW SUBGENUS OF PHENACOMYS 119 



I Geographic distribution of type species and subgenus 119 



II Essential characters of Arborimus 119 



III Description of Phenacomys longicaudus true 119 



1 cranial characters 119 



(1) Skull in general 119 



(2) Back upper molar 121 



(3) Front lower molar 122 



(4) Second lower molar 125 



(5) Third lower molar 126 



2 EXTERNAL CHARACTERS 127 



(1) General coloration 127 



(2) Dorsal coloration 127 



(3) Ventral coloration 128 



(4) Length of tail 128 



(5) Tuberculation of feet and the number of 



mammae 131 



(6) The type of Phenacomys longicaudus 131 



(7) The specimen from Meadows, Lane County, 



Oregon 131 



(8) Pelages 131 



IV Relations of Phenacomys albipcs to the two subgenera 



OF Phenacomys 132 



December 30', 1915. 



