1910] Heller—Mammals: Alaska Expedition, 1908. 343 
were taken in traps set along their numerous runways. Here 
their food consisted chiefly of the wild rye. Their runways 
were much less common in the woods. 
A series of thirty specimens are in the collection. The 
largest exceeds considerably any of the material described by 
Osgood (Proc. Biol. Soe. Wash., XIX, May 1, 1906, p. 71). 
The largest specimen, an adult female, measures: length 225 
min.; tail 49; hind foot 24. The average of the four largest 
specimens is: length 215; tail 47; hind foot 24. The largest 
skull is that of an adult male which measures: Hensel 29; 
zygomatic breadth 19.3; leneth of nasals 9; length of maxillary 
tooth row 7.5. 
This species is easily distinguishable from any other member 
of the genus inhabiting the region by its larger size and much 
darker coloration, the buffy wash on the underparts being much 
heavier than in allied forms. 
Synaptomys dalli Merriam. Dall Lemming Mouse. 
Three specimens from Cordova, five from the Head of Port 
Nell Juan and one from Northeast Bay, Hinchinbrook Island. 
The specimens from these three localities agree very well in 
skull characters, coloration and proportions. They agree min- 
utely in skull characters with the original description of dalli 
(Merriam, Proe. Biol. Soe. Wash., X, March, 1896, p. 62 
Special efforts were made to secure a series of Synaptomys, 
but they are of such rare occurrence in the Sound that only a 
few were taken. At Cordova their runways were found at the 
margin of Eyak Lake amid a tangle of rye-grass, stumps and 
salmonberry bushes. At this locality they were not associated 
with Microtus .kadiacensis. A single specimen was secured on 
a small island in Northeast Bay, Hinchinbrook Island, in a 
Microtus runway at the edge of the forest. More specimens 
were secured at the head of Port Nell Juan than elsewhere. 
Here they were secured in Microtus runways in the open tundras 
in very swampy situations near the beach. 
