50 ARKIV FÖR ZOOLOGI. BAND 14. NIO 4. 



the almost unexplored regions of the eastern slopes and 

 table lands of the Bolivian and Peruvian foot-hills bordering 

 on Brazil, including geographically the head waters of the 

 rivers Acre, Purus, and Juruå.»^ Finally Allén obtained a 

 flat skin from La Candela, »Southern Eastern Andes» of 

 Colombia at an altitude of 6,500 feet.^ These localities are 

 all situated more or less on the eastern slopes of the Andes, 

 where as the specimens of the present eollection decidedly i 

 had their home on the western slopes in Ecuador. The distri- ^ 

 bution of Dinomys is thus much wider than was believed, 

 but the question is whether all specimens known represent 

 identically the same race, or not. At the first look one is 

 inclined to reply in the affirmative to this. F. i. the white 

 pattern of the present specimens agrees completely with that 

 of Peters' plate of the type and also with Goeldi's photos. 

 The latter author says, however, that compared with the 

 Paca »Dinomys has a rougher coat of stiffer hairs, uneven 



in length — and forming a first transition-step towards 



the quills of the coats of the Spiny Råts proper (Loncheridae, 

 Echinomyidae).» Anything like that cannot be observed in 

 the specimens from Ecuador. Their coat is not exactly soft 

 to the touch, but anyway much softer than that of a Paca. 

 Peters does not mention anything about this. 



To make sure about the structure and condition of the 

 hair of Goeldi's Dinomys I took the liberty of writing to 

 Professor Stud er in Bern and of asking him to examine the 

 specimen with regard to Goeldi's statements quoted above. 

 He did so most kindly and explained in a letter, that the 

 unevenness of the hairs at the first look gives the impression 

 that the longer white or white-tipped hairs are somewhat 

 setiform, and he adds, that perhaps this is more visible when 

 the animal is alive. This may account for Goeldi's mistake 

 for in reality the hair of Dinomys is neither thicker, nor 

 stiffer than the hair of the Paca. From this I conclude that 

 the fur of the previously known specimens of Dinomys is not 

 perceptibly different from that of the present specimens. 



An examination of Goeldi's photos appears to indicate 

 that his specimens have rather long tails. One of his figures 

 permits a fairly exact measuring and according to the same 



^ Proc. Zool. Soc. London 1904 II, p. 16L 



2 Bull. Amer. Mus. Nat. Hist. Vol. XXXV, p. 206. 1916. 



