610 Ml-. O. Thomas on 



Dimensions of the type (measured by collector) : — 



Head and body 189 mm. ; tail 195 ; hind foot 47*5 ; 

 ear 27. 



Skull: greatest lengtii 51*5; condylo-incisive length 47; 

 zygomatic breadth 30 ; nasals 16 X 7*8 ; interorbital breadth 

 17'4 ; upper clieek-tooth series 8'6. 



JJab. as above. 



T^/pe. Adult female. B.M. no. 21. 11. 1. 8. Original 

 number 1504. Collected 15th June, 1921. 



The capture of this squirrel by Senor Budin is of great 

 interest, for, altliough an animal believed (and, we now know, 

 rightly believed) to be a squirrel was recorded for Jujuy by 

 Matschie, no determinable specimens have previously been 

 obtained, and the nearest locality to the present hitherto 

 certainly known for them is Northern Bolivia (Sta. Cruz de 

 la Sierra). And even there the squirrel is of the ^^ Lepto- 

 sciurics^^ g'oup, the nearest localities for Mesosciurus being 

 Peru and Colombia. And the species most like tiie present is 

 the S. griseogena, far away in Venezuela. 



Besides the difference in the locality and the absence of 

 any blackening of the tail-tip, S. argentinius is distinguished 

 by its conspicuously reddish ears, a character not known in 

 any of its allies. 



Dr. Allen's great paper on S.-American squirrels being 

 naturally the chief work of reference about them, I pro- 

 visionally use his " Mesosciu7-us" as a subgenus, but 1 should 

 very much doubt if it ought to be considered subgenerically 

 distinct from the far-earlier Guerlinguetus, and should in any 

 case not recognize either Guerlinguetus or Mesosciurus as a 

 genus distinct from Sciurus, with which teeth, penis-bone, 

 and general structure all fully agree. 



In connection with this squirrel I should like to exfiress 

 my sei se of the great loss science has sustained in the death 

 of Dr. Allen, who had worked so much at this group. Both 

 personally and by corresp indence he has been one of my 

 »most valued fi lends and helpers, and the loss of so enthu- 

 siastic a worker makes a sad gap in the ranks of mammalogists. 



Sr. Budin says of this squirrel : — " Native name ' Nuecero ' 

 (which means walnut-eater). I have had much pleasure in 

 obtaining these animals which I have long wished to send. 

 They live among the walnut-trees, and I have had an oppor- 

 tunity of seeing one go into a hole made by the large wood- 

 pecker {Campojihilics leucopogon), wliere it had its nest. 

 They are rare and difficult to see, as at sight of an enemy 

 they remain perfectly still, and are then almost invisible 

 among the branches. All those sent were shot, as I have 

 found it impossible to trap them." 



