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MONOORAPHS OF NOKTH AMKRICAN RODBNTIA. 



is a lietcrogcncous group, cmhracing quite diverse species, some of which 

 strongly approach Scivrus, while others foreshadow Cynomys, and others 

 still grade by almost insensible stages into Tnmias. The group was Rrst dis- 

 membered* by Brandt in 1844, who divided it into two "subgenera'', namely, 

 Colobolis (also written later in the same paper " Olocolobus") and Otoxpcrmo- 

 philus. To the first he referred all the Old World species known to him, and 

 also three of the North American species; the latter is exclusively American. 

 These two groups are based ou slight peculiarities of dentition (particularly 

 in respect to the size and form of the first upper premolar), the size of the 

 ear, and the length of the tail. The Old World species of Colobotit are all 

 short-tailed, with small or rudimentary ears, the tail with the hairs exceeding 

 a length of two inches in only one species {S. eversmanni), being generally 

 considerably less than one-fourth of the length of the head and body. Only 

 one (5. richartboni) of the three American species referred by Brandt to this 

 group really belongs here, the others {8, "hoodi" z= tridecemlineatus, and S. 

 franklini) having few characters in common with the others. Otosj)ermophi- 

 lus is a much more natural division, but was made to include 8. mexicanux, 

 which, as will be shown later, belongs to a wholly different division. The 

 other species referred to Otonpermopkilua were S. grammurus (with its varie- 

 ties and synonyms) and iS?. lateralis; the affinities of the last named are 

 divided between this group and Tamias, with a preponderance toward the 

 latter. Brandt divided the Old World representatives of Colobotis into three 

 sections ("A", "B", and "C"), based wholly on the seasonal and valueless 

 character of the pilosity of the soles, which he appears to have supposed to 

 be a constant character in adults. His section "B" (consisting of S. evers- 

 manni and 8. parryi) he says resembles Otospermophilas in the length and 

 structure of the tail. This is also true of other characters ; it hence forms 

 a natural and well-marked subdivision of his subgenus Colobotis. 



In 1855, Brandt's divisions and subdivisions were adopted by Giebel. 

 Baird, in 1857, while pointing out the worthlessness of any distinctions based 

 on the pilosity of the- soles, thought Brandt's subgenus OtospermophUus enti- 

 tled to permanent recognition, and adopted it with merely the removal there- 

 from of S. mexicanvs to Colobotis, under which latter group Professor Baird 



* Lichtenatoin, however, nbont 1830, propoMd the nsme CHtilltii for oertain ■pcolea, but witbont 

 giving for the gronp any tangible diagnosis. The flnt specie* deioril)ed under this Dome tm S. maci- 

 caniu, bnt he also dfscril)e<l two Old World species (C.fultui and C. nugovtrictu) that differ widely from 

 S. mnieaKM, lielonging in fact to an entirely different section of the genns. Brandt makes, and qnita 

 properly, as it seems to me, CitUl»u merely a synonym of SpermopHliu. 



