56 



BULLETIN 171, UNITED STATES NATIONAL MUSEUM 



broader and with more robust border ridge than in specimens of 

 equivalent maturity. 



The red-squirrel material from the Conard Fissure was referred by 

 Brown (1908, pp. 192-193) to Sciurus hudsonicus. Without a criti- 

 cal comparison of actual material it seems that the Conard Fissure 

 material represents a species close to Sciurus tenuidens, although 

 certain features, as the slightly less robust incisors, the less extreme 

 depth of the lower jaw angle, the apparently larger external auditory 

 meatus, and the more convex longitudinal profile of the posterior 

 portion of the cranium ally it perhaps more nearly to the living 

 S. Jremonti of the Rocky Mountain region. 



Table 16. — Measurements (in millimelers) of skull, mandible, and dentition of 

 Sciurus tenuidens and S. hudsonicus 



Measurement 



Sciurus tenuidens 



U.8.N.M, 

 no. 9197 

 (type) 



U.S.N.M, 

 no. 8164 



U.S.N.M 

 no. 12054 



Sciurut 

 hudsonicus 



U.S.N.M. 

 no. 151654 



(Div. 

 Mamni.) 



Length, posterior margin of incisor alveolus to condyles... 



Depth of rostrum below nasofrontal suture. .- 



Width of skull across postorbital constriction. 



Length of diastema between alveolus for I and P* 



Length of tooth series, P< to M^, inclusive 



Transverse width of M^ 



Depth of jaw below P« 



Length of diastema between alveolus for I and alveolus for 



P4 -- -- 



40.2 

 12.8 

 14.5 

 12.4 

 '7.4 

 12.2 



Length of tooth series from Ft to M3 measured at alveolar 



borders. 



Anteroposterior diameter of lower incisor 



Transverse diameter of lower incisor 



Transverse width of Mj 



4.7 



>8 

 3.9 

 1.3 



8.7 



4.8 



'8.1 

 3.5 

 1.5 

 2.2 



39.5 



12 



13.5 



11 

 7.8 

 2.3 

 8.6 



6.4 



8.2 

 3.2 

 1.2 

 2.2 



• Approximate. 



GLAUCOMYS species 



The flying squirrels are represented in the Cumberland Cave col- 

 lection by a single specimen, a broken lower jaw, U.S.N.M. no. 7687, 

 carrying three teeth, P4 to M2. This fragment of jaw indicates a 

 species larger than Olaucomys volans, not quite so large as G. yukonen- 

 sis, and about the size of G. sabinus. The teeth combine characters of 

 these three living species, with features of theii- own that suggest the 

 specimen may represent a new species, but without more adequate 

 material by which to determine possible ranges of variation it is 

 preferred not to give it a definite assignment. 



The general characters noted in the Cumberland Cave specimen are 

 as follows: Length of cheek teeth series P4 to M2=5.3 mm; greatest 

 width of M2=2 mm. (G. volans length of cheek teeth P4 to M2=4.2; 

 width of M2=1.6 mm.) P4 relatively large, with deep talonid valley 



