30 NELSON 



States, where it is represented in Arizona and western New Mexico by 

 a single species, S. arizo7iensis. The group is most nearly related to 

 Parasciurus from which the skull characters distinguish it. The fol- 

 lowing species and subspecies belonging to this subgenus : S. oculatus^ 

 S. o. tolucce^ S. alleni^ S. nayaritensis^ S. apache^ S. arizonensis 

 and S. a. huacJmca. 



Subgenus PARASCIURUS Trouessart (p1. I, fig. i). 



Parasciurus Trouessart, Le Naturaliste, II, No. 37, Oct. 1880, p. 



292; Cat. Mamm., Rodentia, pp. 77-78, 1880 (part); Merriam, 



Proc. Biol. Soc. Washington, VII, p. 27, 1892. 

 Macroxus Trouessart, Catalogus Mammalium, nov. ed., II, p. 421, 



1897 (part). _ 

 Type Sciuriis niger Linn., from Carolina. 



Distribution. — Eastern half of United States, entering Mexico 

 from western Texas. Upper and Lower Austral (Sonoran) zones. 



External characters. — Size large; body slender; tail long, rather 

 bushy. Upperparts grizzled blackish or yellowish ; underparts black- 

 ish or yellowish. 



Cranial characters. — Premolars \. Skull rather long, rostrum 

 long and broad, nasals broad ; braincase long, narrow, not inflated 

 over parietals and narrowed at occiput. 



General notes. — The subgenus Parasciurus is limited to the Fox 

 Squirrels, S. niger and S. ludovicianus with their subspecies. It is 

 distinguished from Arceosciurus mainly by the long narrow braincase 

 and heavier rostrum. The ranges of the two groups do not touch at 

 any point. 



Subgenus GUERLINGUETUS Gray (p1. I, fig. 7). 



Guerli7tguetus Gray, London Medical Repository, XV, p. 304, 



April, 1821. 

 Macroxus F. Cuvier, Dents des Mamm., p. 162, 1823. (Type, le 



guerlinguet) ; Diet. Class. d'Hist. Nat. X, p. 16, 1826; Lesson, 



Nouv.Tabl. Regn. Anim., Mamm., p. 11 1,1842 (part) ; Gray, Ann. 



& Mag. Nat. Hist., 3d Ser., XX, pp. 271, 419-434, 1867 (part) ; 



Trouessart, Le Naturaliste, II, No. 37, 18S0, p. 292 (part) ; Cat. 



Mamm., Rodentia, pp. 78-80, 1880 (part) ; Catalogus Mammalium, 



nov. ed., II, pp. 421-429, 1897 (part). 

 Type., 'le guerlinguet' — 6". gzierlingjietus Gray (^ Sciurus ces- 



tuans Linn.), from Surinam. 



Distribution. — Tropical America from Peru and Brazil to Nica- 

 ragua. 



External characters. — Size rather small — total length between 300 

 and 450 mm. ; ears long, thinly haired; tail shorter than body, rather 



