1898.] NATURAL SCIENCES OF PHILADELPHIA. 17 



undertone which is pure and bright on the sides of the head and 

 body, becoming almost a pinkish tint on the flanks. Feet and lower 

 surface pure white. 



Tail densely hairy, surpassing in this respect any specimens of 

 either N. floridana or N. mexicana that I have seen. The color of 

 the tail is black above and pure white beneath, the line of demarc- 

 ation being very sharp ; viewed from directly above, the scales are 

 completely hidden by the hairs. The two females in my possession 

 measure as follows : 



No. 156, Collection W. S. 

 No. 157, 



Comparing the skull of N. pennsylvanica with that of N. floridana 

 we find it larger and proportionately longer and narrower. The 

 upper surface is more nearly horizontal (i. e. not so much curved), 

 the frontal bones are much depressed along the frontal suture, the 

 outer edges next to the orbits forming decided ridges. The ptery- 

 goid processes are larger and converge more than in N. floridana, 

 so that the meso-pterygoid fossa is longer and narrower. The upper 

 margin of the infra-orbital foramen as viewed from above is also 

 much narrower in N. pennsylvanica. The teeth are rather heavier 

 than in N. floridana, and the distance between the anterior molar 

 and the incisor (from the alveola?) is relatively greater. 



A table of cranial measurements follows, the measurements of a 

 male (No. 1,129) and female (No. 1,127) N. floridana from Gaines- 

 ville, Florida, Amer. Mus. Nat. Hist, collection, being given for 

 comparison : — 



