PLEISTOCENE VERTEBRATES FROM CUMBERLAND CAVE 59 



Thomomys orientalis Simpson (1928, pp. 6-7) from Saber-tooth 

 Cave in Florida, although possessing characters that ally it to Tho- 

 momys, apparently should be included in the genus Plesiothomomys. 

 The upper incisor in the Florida specimen shows a single shallow 

 groove placed well toward the inner margin of the enamel, as in some 

 modern species of Thomomys. Also, both P* and M^ have the enamel 

 complete across the posterior surface as in the western pocket gopher. 

 However, the columns of these teeth are oval in cross section as in 

 Geomys and the reentrant folds in P^ are not so widely open as they 

 are in Thomomys. Another interesting character observed in the 

 type of P. orientalis is that the rostrum appears to be somewhat 

 depressed anteriorly. This may be due in part to crushing, but the 

 portion of the palate between the cheek teeth and incisors does not 

 seem to ascend so steeply as in living species. 



P. orientalis is a distinctly smaller species with smaller teeth than 



P. potomacensis, corresponding more nearly in size to specimens of 



Thomomys fossor. 



Family CASTORIDAE 



CASTOR CANADENSIS Kuhl 



A single left upper molar in the Cumberland Cave collection, 

 U.S.N.M. no. 12056, may be so exactly matched in specimens of the 

 living species Castor canadensis that it must for the present be referred 

 to this species. Height of crown (apparently not much worn) 23 mm; 

 anteroposterior length, triturating surface, 6.5 mm; actual antero- 

 posterior diameter 6 mm, width 6.5 mm. 



Family CRICETIDAE 



PEROMYSCUS cf. LEUCOPUS(Rafinesque) 



The deer mice are represented in the cave collection by eight frag- 

 mentary mandibles with incisors. Seven of the specimens have one 

 or more cheek teeth each. A comparison of tliis material with jaws of 

 Peromyscus leucopus from the Recent fauna of Maryland failed to 

 reveal any characters of diagnostic importance separating the fossil 

 from the living form. Although more complete material including 

 skulls may show important specific differences, this is not suggested 

 in the mandibles. Several modern species of Peromyscus, as P. mani- 

 culatvs and P. leucopus, have remarkable geographic distribution, and 

 it seems not at all unlikely that their geologic range through Quater- 

 nary time may have been equally extensive. 



NEOTOMA MAGISTER Baird '« 



Figure 32 

 Tliree wood-rat mandibles, U.S.N.M. nos. 12033 (fig. 32), 12034, 

 and 12035, in the collection apparently represent the large Neotoma 



" Baird, 1857, p. 498. 



16541—38 5 



