LYON J SQUIRRELS OF THE SCIURUS HIPPURUS GROUP 2J 



Diag?iostic characters. — Similar to Sciurns hippurus, but larger, and 

 with dorsal portion of the premaxillse distinctly narrower. 



Color. — Sciurus hippurosus so closely resembles S. hippurus that 

 no detailed description is necessary. The underparts average per- 

 haps a trifle lighter in color than they do in the mainland form, and 

 a little more tawny is found in the upper parts. 



Skull. — In addition to its average larger size, the skull of Schuus 

 hippurosus is distinguished from that of its allies by its relatively 

 more slender rostrum, narrow dorsal surface of the premaxillge, and 

 heavier zygomata. (See figure 12, a.) 



Measurements. — See table, page 29. 



Specimens examined. — Three from Tarussan Bay, on the west 

 coast of Sumatra, and one from Besitau River, on the east coast. 



Remarks. — The three specimens from Tarussan Bay are uniform 

 in all respects. That from the Besitan River has the underparts as 

 dark as they are in the peninsula specimens, while above in the 

 middle line the raw sienna color is replaced by rather bright tawny. 

 The skull of this specimen is peculiar in lacking the small upper 

 premolars and shows no place where they might have been. Should 

 more material from eastern Sumatra show these differences to be 

 constant, it would establish the existence of two forms of this 

 squirrel in Sumatra. 



SCIURUS HIPPURELLUS, new species 



Type. — Adult female, skin and skull, Cat. No. 142,274, U. S. 

 N. M., collected at Batu Ampar, on the L,atidak River, western 

 Borneo, July 11, 1905, by Dr. W. L. Abbott. Original number, 

 4260. 



Diagnostic characters. — Similar to Sciurus hippurus, but smaller 

 and with dorsal surface of premaxillae broad. (See fig. 12.) 



Color. — Sciurus hippurcllus so closely resembles 5". hippurus in 

 color that no detailed description is necessary, but it differs in the 

 following particulars : The greater portion of the outside of the 

 forearm is concolor with the back and has only a narrow streak of 

 gray down the forearm instead of the whole outer surface being 

 gray, as in the previous forms ; the thighs are less gray than in the 

 preceding species, being encroached on \>y the color of the back ; 

 traces of the color of the back extend on the upper surface of the 

 tail for nearly one-third its length ; the underparts are a lighter and 

 brighter hazel, inclining to Ridgway's orange-rufous. 



