MAMMALS OF MINNESOTA. 251 



extends a prominent ridge diagonally across the parietals to 

 the median crest of the supraoccipital. The combined width 

 of the parietals is 1.40; two large foramina passing into the 

 squamosals at the point of greatest width just behind and 

 medianly from the zygomatic process of the squamosals. The 

 squamosals are long and narrow, measuring 1.40; the zygomatic 

 process being nearly horizontal and only slightly curved at the 

 very end. The interparietal is so small as hardly to be no- 

 ticed. The skull is flat behind, the supraoccipital being 1.50 

 wide and but 1 high. The par-occipital processes are moder- 

 ately prominent and nearly vertical. The foramen magnum 

 is nearly 0.60 wide and is lemon-shaped. The premaxillary is 

 very large, 0.80 long, and sends up two very large flat plates 

 which incline backward and outward. The opening of the 

 nares is thus an inverted truncate triangle. The premaxillary 

 extends beyond the nasals considerably. The main portion of 

 the maxillary seen from the side is nearly an isosceles triangle; 

 the palatal portion is small and ridgy; the infra-orbital foramen 

 is immense, leaving two slender columns to support the zyg- 

 oma. The palatal is greatly reduced, the last molar being entirely 

 back of the palate. The molar series are inclined to each 

 other at an angle of 30; the outer margins if extended for- 

 ward meeting at the incisor or a little beyond. The malar is 

 1.40 long and greatly expanded anteriorly while its posterior 

 end is knobbed and inflexed. 



The basi sphenoid is 0.55 long, and its pterygoid processes 

 are short but prominent and soldered on to the bullse which are 

 prominent and large. The basioccipital is nearly 0.60 long 

 along the median line. The lower jaw is massive; the angle of 

 the mandible being inflexed, making a large shelf on either 

 side. The condyle with its ascending ramus is blunt and short, 

 while the coronoid process is but an inconsiderable spur on the 

 front edge of the ascending ramus. Length of mandible 2.80; 

 hight of ascending ramus 1.30; length of molar series 1.11. 

 The pattern of the molar crowns seems, at first, very uniform, 

 but a more careful study shows considerable variation. There 

 is an outer and inner enamel layer forming a double wall about 

 the tooth when worn. The size and general contour of the 

 teeth are alike in all of the sixteen teeth, but various minor dif- 

 ferences occur. In general each crown consists of two opposite 

 semilunes united in the middle; each semilune consists of an 

 outer and inner enamel wall, and these may be parallel or the 

 inner one may be folded upon itself. In some cases, between 



