The Lemmings of tJie Genus Synciptomys. 



61 



palate breaks down to the interi)terygoid notch. This rid,i»;e 

 separates the ])Ost-iia]atal ])its and itrojeets liackward into the 

 poSL-i)alatal noteli. In MictomiiS the supraorbital ridges unite 

 in a single median ridge; in Si/iKiploiiiijx they are norrnallv sep- 

 arated by a sulcus. 



The differences in enamel pattern of the molar teeth in the 

 four species of Mictomys now known are shown in the accom- 

 })anying illustration (Fig. 4). The teeth are large and broad in 

 J/, innidtiis and (hdll ; smaller and much narrower in (r/v/y^r/c/i 

 and truei. The reentrant angles on the outer side of the lower 

 molars are deepest in irael i.d'); shallowest in wrangell (I/). 



Fig. 4. — Knaniel pattern of molar teeth in type specimens of 



Mictomvs. X 5- 



a. ft, c\ d, upper series ; a', b', c', d', lower series. 

 (I. Mictomys innuitus. Ft. Chimo, Ungava. 



b. Mictomys turangeli, Wrangel, Alaska. 



c. Mictomys dalli, Nulato, Alaska. 



d. Mictomys truci , Skagit Vallej', Washington. 



Synaptomys (Mictomys) innuitus True. 

 Midomi/.'iimHiHiis True, Froc U. S. Nat. IMus., XVII, 243, April 20, 1894. 



Tt/pe locality. — Fort Chimo, Ungava, Labrador. 



General characters. — Size and general appearance similar to Si/iKiptdnu/s 

 cooperi; ear slightly longer than in Siputpt<))ui/s ; tail shortest of the four 

 known species of Mictomys. 



Color (of alcoliolic). — " Upper surfaces graj'ish brown, as in Synaptomys ; 

 under surfaces gray ; face pale brown ; li[)s, end of nose, and chin white ; 

 feet pale brown; tail bicolored, pale brown above, white below." From 

 continued immersion in alcohol the color of the upper parts has now 

 changed to reddish brown. 



Cranial and dental characters. — Skull as a whole very broad and flat; 

 brain case strongly depressed ; zygomata broadly spreading and standing 

 out squarely from rostrum ; audital bulhe stronglj^ inflated anteriorly, the 

 anterior border strongly convex forward. Contrasted with M. wrangell, 



