WW.] Zoology. 263 



tinge on the belly is more pronounced in some specimens than in 

 others, and in most there is a tendency for the fur in the region of the 

 anus and genital organs to become pure white. The fulvous pectoral 

 spot is absent in two specimens, and in the others varies from a mere 

 trace to an irregular stripe 25 mm. long and about one third as broad 

 in the widest part. The dusky mark at the ankle is conspicuous in 

 some individuals and nearly absent in others. 



The skull of Vesperimus fraterculus resembles so closely that of 

 V. eremicus that I can find no character by which to distinguish 

 them. The number of specimens of eremicus at my digpoea] is, 

 however, too limited to furnish satisfactory data. As compared with 

 skulls of V. americanus, those of V. fraterculus average shorter, with 

 brain case of about equal width and rather flatter. The nasals end 

 in an obtuse angle about 1 mm/short of the premaxillaries. They are 

 narrower than in americanus. The incisive foramina extend about to 

 first third of anterior molar. The articular process of the mandible 

 is shorter, and the coronoid occupies a more posterior position. The 

 posterior upper molar is relatively smaller than in americanus. The 

 following are some cranial measurements of seven specimens of V. 

 fraterculus. 



Number tWf rWV t¥A t 9 ^ tWV rttt tWt 



Sex 2 <? <? £ 9 9 9 



Basilar length 21.4 19 19.8 19 21 20.6 20.8 



Basilar length of Hensel 19 17 17.6 16.4 18.8 18 18.4 



Zygomatic breadth 12.6 12 11.8 11.4 12 12.6 



Interorbital constriction 4 4 4 3.8 4 3.8 3.6 



Greatest length of nasals 9.6 8.6 8.4 8.2 9 8.6 8.4 



Incisor to molar (alveola?) 6 5.2 5.4 5.4 6 5.8 6 



Incisor to postpalatal notch 10.2 8.2 8.8 9 9.2 9.8 9.2 



Height of crown from inferior 



"lip of foramen magnum 7.6 7 7 7 7 6.8 7.4 



Length of upper molar series 



along crowns 3.8 3.8 3.6 3.6 3.4 3.6 3.6 



Length of mandible, exclusive 



of incisors 13.2 11.5 12.6 12.4 13 13 13.2 



Length of lower molar series 



along crowns 4 3.8 3.8 3.8 3.8 3.8 3.6 



— Gerrit S. Miller, Jr., Cambridge, Mass. February, 1892. 



