SQUIRRELS OF MEXICO AND CENTRAL AMERICA 4 1 



Cranial characters. — Premolars \ . The skull (pi. I, fig. 9) of 

 this species is typical of a large group of squirrels in Mexico and Cen- 

 tral America. It is rather short and robust, with heavy rostrum ; the 

 braincase is inflated over the interparietal region; the peg-like ist pre- 

 molar is set barely inside and close to the anterior angle of the 2d 

 premolar. Five adult skulls from Alta Mira average : basal length 

 49.8 ; palatal length 26.5 ; interorbital breadth 19.1 ; zygomatic breadth 

 34.5; length of upper molar series 11. 3. 



General notes. — This strikingly colored species was the first tree 

 squirrel of Mexico and Centi"al America to receive a distinctive scien- 

 tific name, and has figured most prominently in scientific literature. 

 Cuvier published an excellent figure of it with the original description, 

 showing the characteristic bright rufous underparts. The figure repre- 

 sents the less common phase of pelage with but slight extension of ru- 

 fous on the costal area and a poorly defined nuchal patch. By some 

 curious oversight Cuvier, two years later, renamed the species S, leuco- 

 gaster. He gave California as the habitat of this squirrel but men- 

 tioned specimens from eastern Mexico; modern explorations have 

 proved conclusively that it occurs only in eastern Mexico. Later 

 authors have placed it under various names, among which Sciurus 

 variegattts Erxleben has been frequently used, but as I have recently 

 shown (Science, NS., viii, No. 208, pp. 897-8, Dec. 23, 1898), 

 the latter name belongs to a ground squirrel — the so called Spermo- 

 fhilus macrourus of Bennett and other authors. The Scuirus ferru- 

 giniventris of Audubon and Bachman is unmistakably the same as 

 Cuvier's aureogaster., and like it was said to come from California ; 

 and there is little doubt that S. mustelimis of the same authors was 

 based on a melanistic specimen of the same animal. 



Sciurtts aureogaster is separable into three well marked geographic 

 races, of which the one most closely agreeing with Cuvier's figure and 

 description inhabits northern Vera Cruz and southern Tamaulipas. 

 Hence specimens from Alta Mira in southern Tamaulipas are here de- 

 scribed as typical. 



Habits. — This squirrel has a wide distribution in the forests of 

 eastern Mexico, ranging from the coastal plains to the slopes of the 

 Cordillera. On the northern side of the Isthmus of Tehuantepec, 

 Oaxaca, as well as near Orizaba and Jalapa, Vera Cruz, and farther 

 north it commonly ranges up to an altitude of 4000 feet. 



Still farther north it extends back along the deep river valleys far 

 into the interior of Hidalgo and Qiieretaro ; and on the humid, 

 densely forested slopes of the mountains at Pinal de Amoles, Qiiere- 



