aCIURIDiB— SCIUllUS CAROLINBN8I8 VAR. LKUCOTIS. 



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Professor Baird says they arc rare in Eastern Pennsylvania, Maryland, and 

 Virginia. At localities where the pare black phase occurs can usually bo 

 found every intermediate stage between the intensely glossy black individuals 

 and those which scarcely differ from the ordinary type. In Western New 

 York and Northeastern Illinois, where I have had the opportunity of observ- 

 ing the two phases in life, I found that those representing the dusky, oiiudated 

 phase of coloration were young animals, while all the intensely black ones 

 were evidently aged. I felt at the time strongly inclined to the opinion that 

 only the fully mature become intensely black, — in other words, that the 

 intensity of the black increased with age, and that the black Squirrels when 

 young were all more or less annulated with rusty. 



A series before me presents a gradual transition from the usual gray 

 type to the pure black phase. No. 11 oO (Fort D6s Moines, Iowa, Dec, 1855) 

 differs but little above from the usual gray form, except in having a ratlier 

 stronger suff'usion of rufous and less white ; the sides are more strongly 

 reddish-fulvous, and the white area of the ventral surface is narrow and of a 

 rather dingy white, with the breast strongly ochraceous. No. 1136 ( 9, same 

 locality and season) has still less gray ab«ve, the brownish suflTusion is still 

 stronger, and the white of the ventral surface is restricted to a few irregular 

 patches, more or less confluent. There are dusky areas around the teats ; 

 the throat and upper part of the breast are mixed yellowish-brown and black; 

 the inside of the limbs and lower part of the breast are washed with yellow- 

 ish-rufous or gamboge, strongest on the inside of the thighs. No. 1636 

 (Coll. M. C. Z., from Wayne County, 111., Sept., 1867) differs from the last 

 mainly in having the middle of the belly grayish-white, mixed along the 

 median line with pale rufous hairs annulated with dusky; the breast and 

 sides of the abdomen are washed with dingy yellowish-brown. No. 970 

 (West Northfield, 111., Sept., 1855) has the lower parts wit'., a small whitish 

 area divided medially by bright yellowish-brown, the rest of the lower sur- 

 face being gamboge-yellow. The sides of the back from the middle of the 

 body posteriorly are strongly whitish-gray, in strong contrast with the rest 

 of the dursal surface, while the chin, lips, and edges of the fore feet are deep 

 reddish-chestnut mixed with blackish. Next come a considerable series of 

 specimens, obtained in 1847 by Professor Agassiz from the Boston markets, 

 and p-obably killed either in New England or New York, that show various 

 stages of intergradation between the three specimens last described and tli(»Be 



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