SYNAPTOMYS. LEMMUS. 207 



311. truei. {Svnaplomys), Merr., Proc. Biol. Soc. Wash., 1S96, p. 62. 

 Type locality. Skagit Valley, Washington. 



Geogr. Distr. Northwestern Washington, limits unknown. 



Genl. Char. Similar to S. wrangf/i, but more reddish. Last 

 lower molar with deep reentrant angle on outer side. 



Color. Above dull umber brown, grading into plumbeous of the 

 under parts, belly hairs tipped with whitish. Tail, dark above, 

 whitish below. 



Afeasurements. Total length, 112; tail vertebra^ 22; hind foot, 18. 



55. Leinimis. 



I. i^;M. 2=3 ^ 16. 

 I— I 3—3 



Lemmus. Link, Zool. Beitr. Natur., 1795, i, pt. 2, p. 75. 

 Mvodes. Pall., Zoog. Ross. Asiat., 1811, i, p. 173. 



Form stout, compact; nose blunt, hairy: ears small, hidden in 

 fur; tail short, stout, densely haired, penicillate; fore feet large, claws 

 long, fossorial; thumb nearly obsolete with a long, flat, truncated 

 claw; hind feet short, broad, soles hairy, tubercles naked. Skull 

 massive, broad; rostrum short, broad; anteorbital foramen small, 

 almost beneath anterior root of zygoma; bulla; moderate; palate 

 terminating posteriorly in a shelf with or without azygos projection 

 between the penultimate and last molars; ramus of mandible thin, 

 descending process strong, twisted. Molar series long, teeth large. 

 First upper molar with one anterior, two internal, and two external 

 lateral triangles; middle upper molar with two transverse, one inter- 

 nal and one external lateral triangles. Last upper molar with four 

 transverse triangles. First lower molar with anterior ire/oil, one 

 external and two internal lateral triangles, and a lateral posterior 

 loop; middle lower molar with an internal anterior triangle, rest like 

 first molar; last lower molar with external and one internal lateral 

 triangles, and two posterior transverse triangles. All the external 

 reiatrant triangles of upper series very deep as are also the internal 

 angles of the lower series, and the respective saliencies of both acute. 

 Upper incisors beveled laterally, tube-like; root of lower incisor 

 stops in front of last molar. 



312. trimucronatus. {Arvicohi), Rich., App. Parry's 2d Voy., 1825, 



p. 309. 

 all>oguliiris, Wagl., Suppl. Schreb., 1843, iii, p. 602. 

 alascensis, Merr., Proc. Wash. Acad. Scien., igoo, p. 26. 

 Type locality. Point Lake, Lat. 65°. 

 Geogr. Distr. Arctic regions. North America. 



