54 BULLETIN 171, UNITED STATES NATIONAL MUSEUM 



CITELLUS cf. TRIDECEMLINEATUS (Mitchill) 



A single specimen, an incomplete left ramus of a mandible, U.S.N.M. 

 no. 12054, containing the incisor (broken at alveolus), Mi, and Mj, 

 represents the ground squirrels in the Cumberland Cave collection. 

 This specimen is about the size of Citellus tridecemlineatus, to which 

 it is provisionally referred. The two lower cheek teeth preserved 

 are slightly less compressed anteroposteriorly relative to their width 

 than is common in living specimens. The absence of more complete 

 material prohibits a satisfactory comparison with the Recent form. 



TAMIAS cf. STRIATUS (Linnaeus) 



A fragmentary lower jaw, U.S.N.M. no. 12367, included in the 

 rodent material is recognized as belonging to a chipmunk. The 

 lower cheek teeth are present though badly worn, and the incisor is 

 broken away at the alveolar border. The specimen is not complete 

 posterior to the last molar. The jaw is comparable in size and pro- 

 portions to that of the living species, Tamias siriatus. No characters 

 were observed that would serve to distinguish the fossil from the 

 form now living in the same region. 



sciurus (tamiasciurus) tenuidens hay 



Figure 30 



The species Sciurus ienuidens was described by Dr. Hay (1920, 

 pp. 104-105, pi. 4, fig. 20) on what he believed to be an upper incisor 

 in a part of a skull from a cave deposit near Cave town, Md. It was 

 found upon removing the matrix that the specimen is a right lower 

 jaw portion with the lower incisor. The cheek teeth were not pre- 

 served. As an inferior jaw the specimen does not possess such 

 marked characters distinguishing it from Sciurus hudsonicus. The 

 portion of the jaw preserved is rather robust, and the incisor is rela- 

 tively narrow transversely and of greater anteroposterior diameter 

 than in S. hudsonicus. Also, the mental foramen appears to be 

 placed lower on the side of the ramus than in the recent specimens 

 examined. 



Sciurid material in the Cumberland Cave collection includes three 

 skull portions and four mandibular rami. The form represented 

 clearly belongs to the group Tamiasciurus but is apparently distinct 

 from S. hudsonicus. The mandible is more robust and possesses a 

 lower incisor of relatively great anteroposterior diameter and hence 

 presumably represents the Cavetown form, S. tenuidens. On the 

 basis of skull U.S.N.M. no. 8164 (fig. 30a and 6) and a nearly com- 

 plete left ramus of mandible U.S.N.M. no. 12050 (fig. 30c) from 

 Cumberland Cave, the species is redescribed. 



Specific characters. — Size about that of Sciurus jremonti, larger 

 than the average of the S. hudsonicus group. Skxdl with notably 

 broad frontal region and with short, deep muzzle. Viewed from the 



