60 Merriam The Lemmings of the Genus Synaptomys. 

 Synaptomys helaletes gossii subsp. nov. 



Arvicola (Synaptomys) gossii Baird MS., Cones, Monog. N. Am. Kodentia, 

 p. 235, 1877 (nomen nudum). 



Type locality. Neosho Falls, Kansas, No. 6915, $ old, U. S. National 

 Museum. Collected by B. F. Goss, 1866. 



General characters. Similar to S. helaletes, but color probably redder ; 

 rostrum longer; audital bullae smaller. 



Color. Not positively known; probably more reddish brown than in 

 cooperi or helaletes. The mounted specimen in the National Museum has 

 been skinned out of alcohol, and the skins originally collected by Captain 

 Goss cannot be found. 



Cranial and dental characters. Skull as a whole similar to that of S. hela 

 letes, but even larger, with rostrum and nasals longer : zygomata more 

 bowed outward in the middle ; orbital fossae larger ; audital builse smaller ; 

 postpalatal pits deeper, denning a distinct median ridge between them, 

 which ridge projects slightly into the postpalatal notch. Viewed from 

 below, the rostrum and incisive foramina are conspicuously longer. Owing 

 to the small size of the audital bullse, the sides of the basioccipital are 

 less deeply excavated, and the vacuity on each side of the basisphenoid 

 is much larger than in helaletes ; the incisors are very broad and heavy, as 

 in helaletes, and the molars nearly as large (the upper series measuring 7 

 rnm.). 



Measurements. Average of 6 specimens from type locality : total length, 

 120; tail vertebrae, 20.5; hind foot, 19.* 



Subgenus MICTOMYS True. 







A new and exceedingly interesting lemming-vole from Ungava, 

 Labrador, was described by Mr. F. W. True, in 1894, under the 

 name Mictomys innuitas. On comparing the type specimen of 

 this species and specimens of the two related species here de 

 scribed, with Synaptomys cooperi, it appears that the most im 

 portant character separating Mictomys from Synaptomys is the 

 absence of closed triangles or enamel loops on the outer side of 

 the lower molars (Fig. 1). In addition, the upper incisors in 

 Mictomys are more slender and much paler in color, and the part 

 exterior to the sulcus is nearly white, while in Synaptomys the 

 whole enamel face is deep orange. The chief cranial differences 

 are in the post-palatal region. In Mictomys there is a distinct 

 median azygos ridge not present in Synaptomys,^ where the 



* Hind foot from alcoholics ; the other measurements taken in flesh by 

 Captain Goss and converted from Coues' table, N. Am. Rodentia, p. 236, 

 1877. 



f Except in S. aowii in which the post-palatal pits are so deep that the 

 median part of the palate between them is left as a nearly vertical pro 

 jection comparable to, but much shorter than, that of Mictomys. 



