Vol. V] TAYLOR— NEW SUBGENUS OF PHENACOMYS \\C^ 



As regards their habits the MicrotincB are notably adapt- 

 able. The situations in which they are found are many 

 and varied. They are encountered ". . . from sea 

 beaches to marshes and Alpine mountain tops, and from 

 open plains to the densest forests .... While the great 

 majority of species spend much of their time on the sur- 

 face, protected by the overhanging vegetation, a few live 

 almost exclusively underground, and in consequence of this 

 habit have acquired numerous modifications which fit them 

 for the needs of a subterranean life. Others are amphibi- 

 ous and never occur at any great distance from water" 

 (Miller, 1896, p. 10). Of all members of this great sub- 

 family, Phenacomys longicaudus is unique in its choice of an 

 arboreal habitat; and we may well inquire as to whether 

 this peculiar habit may not be weighted as of importance in 

 the classification of the species. The use of habit characters 

 is not without precedent in the Microtince. Before the pub- 

 lication of De Selys Longchamps' "Essai Monographique sur 

 les Campagnoles des environs de Liege," 1836, the voles 

 had been divided into two groups according to their habits, 

 the aquatic species being separated from those that are strictly 

 terrestrial. But beginning with and subsequent to this 

 author habits as characteristics of the organism appear to 

 have been left out of count in the classifications of the group. 



Miller (1896, p. 24) has clearly shown the impracticability 

 of the subdivision of the genus Micro tus, and the same holds 

 with regard to the subfamily Microtin(E, according to the 

 variations in any one set of characters, and in his own work 

 bases the classification upon an assemblage of characters, all 

 drawn from the province of physical peculiarities. Of these 

 the following are regarded as the more important: form of 

 skull, structure of bony palate, pattern of enamel folding, 

 number of mammae, number of plantar tubercles, and pres- 

 ence or absence of musk glands on the sides. Regarded as of 

 lesser importance are : quality of fur, hairiness of soles, length 

 of tail, form of front feet, size of eyes, and form of ex- 

 ternal ear. 



It would appear that the greater the assemblage of char- 

 acters on which a classification is based, so long as such char- 

 acters are comparable in degree of constancy, the more ade- 



