204 Bulletin American Museum of Natural History. [Vol. XXXIV, 
In 9 specimens examined, all from central Peru, the ventral surface is 
wholly red in 1, wholly white in 4, and red patched with white in 4 others. 
“Head and body, 240 mm.; tail, 208; hind foot (wet), 59; ear (wet), 21. 
“Skull: greatest length, 52; basilar length, 46; greatest breadth, 33.5; 
nasals, 16.5 X 8.4; interorbital breadth, 18; intertemporal breadth, 19; 
diastema, 15.2; palate length from hensilon, 26.7; length of upper tooth- 
series, 9.6.’’ — Thomas, J. c. ‘ 
Specimens examined, 9.— Peru: Chanchamayo, 7, including type 
(Br. Mus.); Chanchamayo, 2 (Field Mus.). 
Remarks.— Mesosciurus pyrrhinus presents a remarkable similarity to 
M. saltuensis bond, considering the remoteness of their ranges, which are ~ 
separated by more than 2000 miles. In size, cranial characters, pelage, 
pattern of coloration, and in color, they are so similar that were their ranges 
contiguous there would be no reasonable ground for not considering their 
relationship as merely subspecific. In the saltwensis group the ventral 
surface is white, in pyrrhinus it may be either white or red, or a patchy 
mixture of both, and there is a stronger mixture of black in the basal third 
or half of the tail. 
This species was described and figured (both the red-bellied and white- 
bellied phases) by Tschudi (/.c.), under the untenable name Sciurus variabilis, 
who states that it is abundant in the forest of the eastern slope of the Andes 
between latitudes 9° to 12° south. 
8 
Genus Guerlinguetus Gray. 
Text Figs. 8, 15 (pp. 163, 165); Plate IX, Figs, 4-6; Plate XIII, Figs. 19-24. 
Guerlinguetus Gray, London Med. Repos., XV, p. 304, April, 1821 (genus) .— 
NELson, Proc. Washington Acad. Sci., I, pp. 30, 98, pl. i, fig. 7, May 9, 1899, part 
(subgenus).— Mier, Bull. 79, U.8. Nat. Mus., p. 334, part (subgenus). 
Macroxus F’. Cuvirr, Dents de Mamm., pp. 161, 162, 255, pl. lvi, 1823.— LESSON, 
Gray, TROUESSART, and others, in part. Type, by designation of Thomas, 1897, 
Sciurus estuans Linné. 
Type (by tautonymy), le querlinguet Buffon = Myoxus geurlingugus 
Shaw = Sciwrus guerlinguetus Gray = Sciurus estuans Linné. 
size small; mamme, 8; tail long, about 50% of total length. 
Premolars, ¢. Skull long and narrow; dorsal outline less convex than in 
Leptosciurus, Notoscturus, and in most forms of M esosciurus; malar narrow, 
slightly expanded vertically on the upper border, which is depressed behind 
the malar process; m! and m? of the usual sciurid type (nearly as in typical 
Sciurus), with the cusps on the outer border well developed, as are also the 
intervening cusplets, differing thus strongly from those of Leptosciurus, 
