250 MICROTIN^ 



representative set of specimens from Scandinavia (including some 

 received from Sundevall) ; a series from the Syansk Mountains, 

 100 miles west of Lake Baikal, collected by D. Carruthers ; a very 

 fine series from the neighbourhood of Lake Baikal, province of 

 Irkutsk, collected by G. A. Burney; and three specimens from 

 Kamtschatka obtained by Barrett-Hamilton. It thus affords 

 topotypical material not only of Sundevall's E. rufocanus, but of 

 the nominal forms E. r. latastei Allen, E. irkutensis Ognev, and 

 E. hargusinensis Turov, as well. What is equally important, it 

 represents all stages of growth, from the young with a skull of only 

 19-3 mm. in condylo-basal length to an aged individual with a 

 skull measuring 27-2 mm. and cheek-teeth provided with long roots. 

 After carefully studying this material and the literature cited 

 in the synonymy I can find no good reason for believing that there 

 is more than one form of E. rufocanus within the vast area in- 

 dicated above. For completeness' sake the following notes on 

 the characters attributed to the nominal forms are given : — 



(1) E. r. latastei Allen, is said to be distinguished from the 

 typical form by its much smaller size, less angular teeth, rounder 

 auditory bullae, less fulvous under parts and darker grey sides. 

 As evidence of the smaller size Allen gives the following measure- 

 ments of ten " adults " from Gichiga, northern Kamtschatka : — 

 total length 128 (120-140) mm.; tail 29 (24-^3); hind-foot 19 

 (18-20); and for the skulls of six " adults "' : — total length 23-6 

 (22-5-25); basal length 20-5 (19-22); zygomatic breadth 13 

 (12-13-8); nasals 6-2 (5-7-6-5). These statements indicate, in 

 my opinion, that Allen's material is not adult but immature; 

 making allowance for this and for possible differences in the 

 methods of taking the external measurements his account of 

 E. r. latastei discloses no solid reason for separating this form from 

 typical E. r. rufocanus. The few specimens from Kamtschatka 

 before me are adults and they appear to agree in every respect with 

 those from Scandinavia. 



(2) E. r. hargusinensis Turov. Dr. Turov has kindly furnished 

 the following diagnosis : — " Longitudo corporis minor quam in 

 typica E. rufocanus, corporis longitudo 90-2-102. Planta exclusis 

 unguibus multo minor (16-8-17-8) quam in forma typica. Cran- 

 ium minus, longitudo condylo-basalis 25-4-27-6 ; spatium interor- 

 bitale angustum (3-6-3-8). Ossa nasalia longiora quam in forma 

 typica (ad. 8-5). Dentium molarium series brevior (6-6-6). Color 

 opaco-fuscus plerumque in rufum vergens vix distinguitur a 

 forma typica colore, griseo in capitis lateribus atque corporis 

 lateribus fulvo brunnescentibus." The facts (as distinct from the 

 comparisons) recorded in this diagnosis, seem to me to agree 

 perfectly with those observed in typical E. rufocanus ; moreover 

 Mr. Burney's fine series from the north-western shore of Lake 

 Baikal is practically topotypical of E. " hargusinensis,'' and I am 

 quite unable to distinguish these specimens from those from 

 Scandinavia. 



