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seems to be between parvus and lordi . There are some good reasons for 
supposing that all the Perognathus forms of southern British Columbia 
and northern Washington are varieties of a single species, which by priority 
would be Perognathus parvus (Peale) 1 , making Perognathus lordi lordi (Gray) 2 
a subspecies of P. parvus. However, there are still some wide gaps in the 
ranges of these forms which are biologically little explored, and in the 
present state of our knowledge it seems best to consider Perognathus 
laingi as a distinct species of the parvus “group.” 
Remarks. Mr. Laing informs me that the area where P. 1. lordi 
was most abundant was at lake-level of Osoyoos lake (913 feet altitude), 
and the workings gradually lessened as the timbered summits were ap- 
proached both on the east and west sides of the lake. There may have 
been a gap between the lake-level form (P. lordi ) and the form (P. laingi ) 
from near the summit of Anarchist mountain, but it was not very extensive, 
although there may be a gap of several wooded miles where it would be 
difficult to find this mouse. The difference in habitat is very striking. 
The floor of the valley of Osoyoos lake is the most desert spot in Canada, 
with whole flats covered with antelope brush (Purshia tridentata D.C.), 
whole benches and slopes a little higher covered with rabbit brush (Bigelovia 
graveolus Nutt.), and nearly every clump of either of these plants had a 
mound of P. lordi at its feet— new or ancient. 
There was also a great deal of sagebrush (Artemisia sp.) and the 
pocket mice w r ere in this, too, but not to the same extent. On the other 
hand, the colony of the blackish form (P. laingi ) was found on the southern 
face of Anarchist mountain, using the roadside ditch, the usual groove 
at roadside made by scraper, to kick out their mounds the same as the 
others did at low elevations, but this was a different type of country, 
with wheat fields on either side of the road, where dry-farming has been 
practised for years. The elevation here in the woods showed the western 
larch (Larix oecidentalis Nutt.), Douglas fir (Pseudotsuga taxifolia (Lamb.) 
Britt.), yellow pine (Pinus ponderosa Dough) association. 
In the interior of southern British Columbia an increase in altitude 
generally means more precipitation and more luxuriant vegetation, and 
as pale colours in birds and mammals are usually associated with aridity, 
the darker colours of P. laingi as compared with P. lordi of the lower 
levels seem to reflect the altitudinal and climatic conditions. 
Thanks are due to the Chief of the Biological Survey, United States 
Department of Agriculture, Washington, for the loan of specimens of 
P. parvus for comparison. 
Specimens Examined. Eleven from Anarchist mountain, British 
Columbia (topotypes): four adult males, one juvenile male, one adult 
female, five juvenile females, taken August 29, 30, and 31, 1928; all in 
collections of National Museum of Canada, Ottawa. 
l Cricetodipus parvus Peale, U.S. Expl, Exped., VIII, Mam m . and Ornith., pp. 52-54 (1848). 
1 Abromys lordi Gray, Proc. Zool. Soc. London, p. 202 (1808). 
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