882 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



boothiw, and which were really the basis of what I recognized as 8. liypo- 

 pyrrhus. I associated with them, however, specimens representing the 

 8. dorsalis of Gray, from their apparently slenderer form and relatively 

 longer ears and tail. Although Mr. Alston has not seen the types of 

 either Wagler's S. lujpopyrrlius or of 8. stramineus, I defer for the pres- 

 ent to his judgment in adopting hypopyrrhus as the name of this highly 

 polymorphic group. 



Under 8. hypopyrrhus, Mr. Alston recognizes five " types", namely: 

 1. "The hypopyrrhus type", to which he refers S. nigrescens, Bennett, and 

 Macroxus boothice, Gray, 1867. 2. "The rigidus type", to which he refers 

 S. rigidus, Peters, S. intermedius, Yerreaux, and 8. nicoyanus, Gray. 

 3. " Thedorsalis type." 4. u Thecolliwi type", to which he refers 8. collicei, 

 Eichardson, 8. adolphei and 8. pyladei, Lesson, 8. variegatoides, Ogilby, 

 S. oculatus, Peters, and 8. griseocaudatus, Gray. 5. " The melania type " 



u With regard to the synonymy," Mr. Alston writes, "I may ob- 

 serve that I have been able to examine the types of all the ' species ' 

 here united, excepting that of 8. hypopyrrhus, which, however, has been 

 well described by Wagler and Wagner ; it appears to be a dark variety 

 without the usual wash of white on the tail. ..." 



"Qf the geographical distribution of the races," he says, " we can 

 only judge from the comparatively few specimens of which the exact 

 localities have been noted. Tbe hypopyrrlms phase appears to be the 

 most northern, the collicei to obtain principally along the Pacific slopes, 

 and the dorsalis to be the most southern. Each, however, appears to be 

 found along with the others in some parts. Thus, I have seen speci- 

 mens of the hypopyrrhus type from Mexico, Honduras, and Guatemala, 

 of rigidus from Guatemala, Nicaragua, and Costa Rica, of dorsalis from 

 Nicaragua, Costa Rica, Yeragua, and Panama, and of collicei from the 

 west coast of Mexico and Guatemala, Nicaragua, and Oosta Rica. The 

 only .localities which I know for 8. melania are Nicaragua and Yeragua."* 

 In all probability, these five types will prove to be entitled to varietal 

 rank. 



IX. SCIURUS AUREIGASTER, F. Cuvier. 



Sciurus aureogaster, F. CUVIER, Hist, des Mara, iii, livr. lix, 1829. 



ticiurtw leucogaster, F. CDVIER, Suppl. de Buff, i, Mam. 1831,300. 



Sciurus albipes, WAGNER, Abb. Bayer. Ak. ii, 1837, 501 (according to Alston ; formerly 



referred by me, vitb a ?, to the preceding species). 



Sciurus socialis, WAGNER, Abb. Bayer. Ak. ii, 1837, 504, pi. v (according to Alston). 

 Sdurusferruginiventris, AUDUBON & BACHMAN, Proc. Acad. Nat. Sci. Pbila. 1841,101; 



Quad. N. Am. pi. xxxviii. 

 Sdttrus varius, WAGNER, Suppl. Schrebers Siiuget. iii, 1843, 168, pi. cccxiii D ("S. al- 



lipes" on plate ; = S. albipes, Wagner, 1837). 



Macroxus mono, GRAY, Ann. and Mag. Nat. Hist. 3d ser. xx, 1867, 424. 

 Macroxus rnaurus, GRAY, Ann. and Mag. Nat. Hist. 3d ser. xx, 18C7, 425 (formerly referred 



by me to tbe preceding species). 



Macroxus leucops, GRAY, Ann. and Mag. Nat. Hist. 3d ser. xx, 1867, 427. 

 Sciurus aurdgaster and S. leucops } ALLEN, Mon. N. Am. Rod. 1877, 750, 753. 

 Sciurus variegatus, ALSTON, Proc. Zool. Soc. Lond. 1878, 660 (ex Erxleben). 



* Loc dt. pp. 663, 664. 



