24 BULLETIN : MUSEUM OF COMPAEATIVE ZOOLOGY. 



Sciurus (Microsciurus) bro-wni,i sp. nov. 

 Type. — Mus. Comp. Zool., No. 10,404, old ad. $ Bogaba, July 15, 1901. 



Five specimens, both sexes, Bogaba, July. 



Characters. — Probably nearest to S. alfari Allen, from Costa Rica, but dif- 

 fering in many respects from that species. Pelage much thinner, less woolly ; 

 upper parts decidedly more olivaceous — lacking the reddish brown of S. alfari \ 

 tail thinly washed with grayish white instead of dull rusty ; nose, forehead, 

 and orbital ring more tawny ; under parts much paler ; in the new species dull 

 gray slightly washed with bufFy in some specimens, yellowish white in others, 

 on under side of neck and middle of belly, in 5. alfari the under parts are dull 

 rusty on under side of neck and breast with a thin wash of this color extend- 

 ing back over bell)'', which has a dull brown shade. 



The skull is similar to that of 5. alfari, but the brain case is narrower, more 

 rounded and without so marked a constriction in front of the occiput, and with 

 the mastoid region less prominent. 



Color and Pelage. — Pelage short and thin, rather harsh and with but little 

 under fur. 



Upper parts, a fine mixture of tawny olive and bistre, produced by the dark 

 brown bases and tawnj^ olive tips of the hairs ; nose, forehead, and orbital ring 

 tawny ; tail with the hairs dark reddish brown basally then black and tipped 

 with grayish white, a small black pencil ; under parts dull gray to grayish 

 white, slightly washed with buffy or yellowish (in some specimens, very slightly 

 in the type) on under side of neck and middle of belly ; under sides of legs 

 darker — more nearly like upper parts. 



Skull, type, adult 9 > basal length, 29 ; occipitonasal length, 36 ; zygo- 

 matic width, 21.2; interorbital width, 12.4; palatal length, to palatal notch, 

 13.4 ; to end of pterygoid, 20.2 ; length of nasals, 11 ; length of upper molar 

 series, 5.8. 



Remarks. — Mr. Brown found this little squirrel in the forest about Bogaba, 

 at 600 feet altitude. It was rare and exceedingly hard to get, on account of 

 its small size and dull coloring, and only by devoting much time and energy 

 to the chase did he succeed in taking five specimens. 



Mr. E. W. Nelson has compared very carefully these five specimens with 

 the type of Microsciurus alfari Allen, and agrees with me as to the specific dif- 

 ferences between these two tiny tree squirrels. 



1 Named for Mr. W. W. Brown, Jr. 



