E. LÖNNBERG, MAMMALOGY OF ECUADOR. 35 



to guayarius. The stränge thing is tliat Thomas had his 

 type-specimens of guayanus from the Balzar Mountains north- 

 west of Guayaquil, but Allén records the typical stramineus 

 from Guayaquil. It is, however, possible that either Rio 

 Palenque or Rio Balzar forms the boundary line between 

 these two races, and that Allen's specimens, although from 

 the neighbourhood of Guayaquil, had been collected on the 

 eastern side of this line. But it may also be possible, that 

 more material will prove, that the individual variation of 

 these Squirrels is so great, that the racial difference cannot 

 be maintained. 



Allén has in his Monograph quoted established a new 

 genus for the Squirrels of the stramineus-gvow^p. He names 

 this Simosciurus, which name he probably has based on an 

 expression which he uses in the diagnose viz.^ »Skull short, 

 due mainly to the extremely short rostrum»; and he adds: 

 »nasals very broad and short, about 22 % of the total length 

 of the skull and only about 60 % of the interorbital breadth, 

 instead of 90 % as in Urosciurus.» If these latter state- 

 ments are compared with the exact cranial measurements of 

 S, stramineus stramineus recorded by Allén (1. c. p. 282), 

 which also agree with the corresponding ones of the present 

 skulls, it will be seen that these percentages as stated by 

 Allén in the diagnose of the genus Simosciurus must be 

 due to a miscalculation, as is set fort belo\;v. The average 

 total length of five skulls of S. s. stramineus is according to 

 the author quoted 58, and the average length of the nasals 

 of the same skulls 16 mm. The latter dimension is then 

 27,5 % of the former (not »about 22 %»). The average inter- 

 orbital breadth of the same skulls is according to the author 

 quoted 19 mm. The length of the nasals is thus 84,2 % of 

 the latter measurement (not »about 60 %»). 



Allén has pronounced that the characteristics, which he 

 has derived from the above quoted relative dimensions, should 

 constitute an important difference between his genera Simo- 

 sciurus and Urosciurus, and if there had been no mistake 

 with regard to the percentages, this might ha ve been the 

 case. With the above made correction it may be found, that 

 the relation between the length of the nasals on one side, 

 and the total length of the skull, resp. the interorbital breadth 



' ]. c, p. 280. 



