REMARKS ON THE GIANT SQUIRRELS OF SUMATRA, 

 WITH DESCRIPTIONS OF TWO NEW SPECIES. 



By Marcus Ward Lyon, Jr., 



Assistant Curator, Division of Mammals, U. S. National Museum. 



The I^. S. National Miiseuni has m its Qollections 49 specimens of 

 giant sqiiiiTels, genus Ratufa, from various parts of the island of 

 Sumatra, all but two of which have been collected and presented by 

 Dr. W. L. Abbott. I have also had at my disposal three specimens of 

 Sumatran Ratufa belonging to the collection of the Academy of 

 Natural Sciences of Philadelphia. To Mr. Witmer Stone of that 

 institution my thanks are due for the use of them. 



The giant squirrels on ^Sumatra fall into two distinct groups, repre- 

 sentatives of which are found side by side in the same localities. 

 Members of the palliata or hicolor group are known by their larger 

 size, as well as by their dark heads, necks, shoulders, rumps, legs, and 

 feet. Only one form of this group is at present known to occur on 

 Sumatra. The hypoleuca group, so called from the first species 

 described from Sumatra, contains smaller members than the other 

 group, with white or buffy underparts, and with uniformly light 

 brownish upper parts. Three well-marked forms of this group are 

 found on Sumatra — typical hypoleuca. on the w^est coast, and two new 

 species on the east coast. (See map, Plate XXXIII.) All the forms 

 of Sumatra giant squirrels may be readily known by the following 

 key and descriptions: 



SYNOPSIS AND KEY TO THE GIANT SQUIRRELS OF SUMATRA. 



A. Upper surface of head, neck, shoulders, arms, legs, and feet black or blackish 

 brown, different in color from the sides and rest of upper parts. 



Ratufa palliata, p. 440. 



A'. Entire upper parts and sides uniform light yellowish brown, sometimes becoming 



darker along the middle line of the lower back. 



B. Underparts white or whitish, feet concolor with legs, size large; head and body, 



340 to 370 mm.; tail, 400 to 435; hind foot with claws, 79 to 84; greatest length 



of skull, 65 to 67 Ratufa hypoleuca, p. 441. 



Proceedings U. S. National Museum, Vol. XXXII— No. 1534. 



439 



