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742 



MONOGRAPHS OF NORTH AMERICAN RODENTIA. 



Maerozim hoolhlo' Gray, Ann. and Mng. Nnt. Iliot. 3i1 Her. xx, 1R67, 424. 



JUacroxi'H niuii/ana Uiiay, Auu. nud Mag. Nut. Hist. 3d ser. xx, 1HC7, 423 (Costa Rica). 



Macrorns colliai Giiay, Ann. and Mni;. N»t. Hint. 3<1 aer. xx, 18G7, 421 (vara, t and 2 only). 



" iS'ciui'iK intermediuH Vki<urai?x " (MS. nntuo f ; see Gray, 1. c. 421). 



Sciurut rigidua IVi'Eiis, Muuatsb. Kiiuigl. I'rouiM. Akod. WiDseniich. zu Berlin, 1863 (1664), Go2. 



Specific chars. — Form rather stout; muzzle short and broad; ears rather 

 small ; tail narrow, rather longer than head and body ; pelage full, coarse, an«l 

 long. Length of head and body 12.50 ; of tail-vertebroe 9.75 ; of tail to end of 

 hairs 12.75. Above, dark brown, mixed with yellowish-gray or black, varied 

 with fulvous ; often paler on the sides, where there is a tendency, in many 

 specimens, to a broad, grayish, sub-lateral band ; beneath, deep brownish-rrd, 

 frequently with unsymmctrical patches of pure white. Tail below tricolored, 

 centrally rufous, then black, with a border of white; the rufous in the nii<Idle 

 variable in amount and in tint, sometimes obsolete, sometimes forming a 

 broad central l)and of bright rufous, at other times pale rufous. 



This species is so variable in coloration as to be hard to characterize. 

 The above diagnosis indicates a condition intermediate between the extremes, 

 as well as apparently the most common phase. Of eighteen Costa Rican 

 specimens, about half present a quite uniform style of coloration, while of the 

 remainder, no two are very nearly alike. Eleven agree quite nearly in having 

 the general color above black, varied more or less with reddish-brown, the 

 proportion of the two colors varying with each specimen. The ventral sur- 

 face in all, including the inner side of limbs, is dark reddish-orange. The 

 pelage above is black at base, witii a broad subterminal band of fulvous- or 

 rufous-brown, the hairs all broadly tipped with glossy black. The sides of 

 the head, nose, and chin are grayish-brown ; the ears liave a rufous spot at 

 tile base posteriorly. The hairs of the tail are fulvous (in some specimens 

 rufous) at base, ringed with black, then crossed by a broad band of black and 

 narrowly tipped with white. The color of the central portion of the lower 

 surtace varies from fulvous to dark brownish-red. Another specimen (No. 

 11410) is similar to these, but has less black above, and the rufous of the 

 ventral surface is paler; the tail is rufous centrally near the base and toward 

 the tip. No. 113G4 has still less black above, and the lower surface is irreg- 

 ularly marked with large patches of pure white. The tail is also much more 

 broadly edged witii white, and the ear-patches are also white, as they are in 

 the mnjority of the specimens before me. No. 930G differs little fn)in the 

 last, except in having rather less black above, and in a tendency tu a pale band 



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