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748 



MONOGRAPUS OF NORTH AMERICAN RODENTIA. 



niid lliront pale fulvous. The tail liiis also the hairs of the lower surface pale 

 }cil()\visli at the base, then black, broadly tipped with white. These speci- 

 mens, judging from De Saussure's description, are the more cominon.or normal 

 plinsc of tiic species. No. 8495, from Nicaragua, is white, except a broad 

 dorsal band, extending from the occiput to the tail, which is intense brownish- 

 black. The hairs of the lower surface of the tail are white at base, then 

 black, broadly tipped with white, giving a wholly pure white surface to the 

 fail tiirough'v.t. No. 8628, from Costa Rica (^about half-grown), has the 

 whole body pale yellow or yellowish-white, with an indistinct brownish dor- 

 sal band. The hairs of the tail arc wholly black at base, broadly tipi)ed 

 with whitish. Two other specimens, from Southern Mexico, are almost 

 wholly' black, being only slightly varied with gray above and on the tail. 



This species difTers from most other American species in its slcnderness, 

 the great length and narrowness of the ears, and the excessive length of the 

 tail, which, with the hairs, is one-fifth to one-fourth longer than the head and 

 body. Dr. Gray's S. dormlh agrees perfectly with the white, black-backed 

 specimen (No. 8495) above described. The Macroxus melania of the same 

 author corresponds with the black phase of this species, and his M. maurvs. 

 with the black phase which has the under parts more rufous. De Saussure, in 

 his paper on the Mexican Squirrels (as above cited), describes this species 

 as being usually fcrrugineous beneath,* but gives the following phases of col- 

 oration under the head of three unnamed varieties: — a, wholly black, with 

 the hairs more or less fulvous at the base; b, blackish, with the ventral sur- 

 face gray, fulvescent, or dusky; c, body wholly black. 



The original description of Waglcr refers to a phase with the lower 

 parts strongly rufous. The length is given as 12 inches from the nose to the 

 end of the tail; the tail (vertebra: only?) as 11.75. Wagner gives the length 

 from nose to base of tail as 12 inches; of the tail- vertebrae 12.09; tail to end 

 of hairs 14.75. 



I am quite confident that the Sciurus nigrescens of Hcnnett, described 

 in 1833 as "from that part of California that adjoins Mexico", is referable to 

 the dark phase of the present species. The great length of the tail as com- 

 pared with the bodyt renders it almost certain that it can refer to no other 



"'Subtug iufo-l'«rru|;iueuB, frvqiivnter piliB uigriM iiiterniixti*, ui«nto ui|{r«8C«iite."— (Arr. r( 

 Mag. de Zool. 18C1, p. 5.) 



t Acconling lo Beonetf, bend and body 10X0; tail-vertebrio IO.SO; tail to end of bain 14.00 ; or, 

 according to Bacbuian's meaiinrenieota of the aauie specimen, bead and body 18.37; tail to end of 

 bairs 10.37. 



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