88G BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



differing in its uniformly larger size and strikingly in the coloration of 

 its tail. In a subsequent letter to me he says : 4 It would perhaps be 

 just as well to recognize it as entitled to specific rank, although I still 

 feel sure of their intergradation.' That such connecting links may yet 

 be found seems very probable ; but I have not been able to find such in 

 the very large series which I have examined, and am consequently com- 

 pelled to keep them provisionally distinct. Unfortunately Mr. Allen has 

 identified this species with Pucheran's S. rufo niger, which, as will be 

 seen presently, is a much smaller and quite distinct species. Dr. Peters 

 described it only as a variety of #. ccstuans ; and though specimens in 

 the Berlin Museum are labelled l Sciurus lioffmanni\ the name remains a 

 manuscript one. Of Gray's three titles I have adopted griseogena (more 

 correctly griseogenys) as being simultaneous in date with the others, and 

 as indicating the typical form." ALSTON, 1. c. p. 667. 



Accepting provisionally this Squirrel as specifically distinct from S. 

 (jestuans, I dissent from the foregoing only respecting its proper title. 

 Although the name lioffmanni may remain a manuscript one as applied 

 in a specific s$nse, its publication as a varietal name for this form, three 

 years prior to the publication of Gray's names, appears to me to warrant 

 its use as a specific designation for the same form. Such a procedure 

 has certainly the sanction of numerous precedents. 



XY. SCIURUS RUFONIGER, Pucheran. 



Sciurus rufonigfir, PUCHER4N, Rev. de Zool. 1845, 336. ALSTON, Proc. Zool. Soc. Lond. 



1868, 669. 



Sdurus chry&urus, PUCHERAN, Rev. de Zool. 1845, 337. 

 "Macroxus tephrogaster minor, GRAY, MSS." apud Alston. 



NOTE. This species I introduce entirely on the authority of Mr. Alston, 

 who has examined the types. I referred both of Pucheran's species 

 unhesitatingly to the preceding species, but the presence of two upper 

 premolars in S. rufoniger would seem to render it unquestionably distinct 

 from S. lioffmanni, and to ally it with S. deppei (as perhaps the young of 

 that species). 



Kespecting this species, Mr. Alston remarks as follows : " On examin- 

 ing the type of Pucheran's S. rufo-niger in the Paris Museum, I found 

 that it was not identical with S. griseogenys [8. cestuans var. rufoniger, 

 Allen, Mon. N. Am. Rod.], as Mr. Allen supposed, but rather allied to 

 S. deppei [S. tephrogaster, Allen, I. c.\ ; and I soon recognized in it a small 

 Squirrel from Panama, and which I had begun to fear would require a 

 new name. These examples prove to agree further with S. deppei in 

 having two upper premolars, but differ in being more than one third 

 smaller, in the color of the lower parts (which are only paler than the 

 upper, save on the breast), and in the tail being nearly uniform in color 

 with the back (the hairs having only very minute white or yellow tips). 

 Specimens in the British Museum are labelled M. tephrogaster minor ; 

 but I cannot doubt the distinctness of the form. The type of S. rufo- 



