1896.] NATURAL SCIENCES OF PHILADELPHIA. 183 



East Tennessee. Those from West Tennessee apparently resemble 

 sylvaticu8 from Pennsylvania and New Jersey, but not having sum- 

 mer skins from the Eastern States, the determination is unsatisfac- 

 tory, Mr. Bangs" identified three winter specimens from Trenton 

 (Gibson Co. ?) Tennessee, as " perfect intermediates between sylva- 

 ticus and mearnsi, both in size and color." 



Regarding the possible occurrence of L. sylvaticus transitionalis 

 Bangs, in the Great Smoky Mountains, its describer writes me : 

 " I examined a large series last winter from Roan Mountain, and 

 they were all true sylvaticiis." 



Specimens — Samburg, 5 ; Raleigh, 1. 



Genus SYNAPTOMYS Baird. 

 7. Synaptomys cooperi Baird. Lemming Vole. 



Six specimens, a lately nursing female and five young, the latter 

 apparently belonging to a single litter, and the former probably 

 their parent, were trapped in a small, springy place on the Caro- 

 lina side of the summit of Roan Mountain, where a quantity of 

 their favorite tussock rush, Juncus, was growing. The adult is in- 

 distinguishable from Massachusetts and Pennsylvania specimens. 

 The young are of much interest, no record or description of im- 

 mature specimens having yet been published, to my knowledge. 

 They are about half grown, their average measurements being, 

 total length, 85 millimeters; tail vertebrae, 13; hind-foot, 18.5. 

 Above, including the sides, they present a uniform blackish gray 

 shade, which close examination detects to be obscurely mixed with 

 dull wood brown. The prevailing hue is due to the long and very 

 numerous dull black hairs, which are sparingly mingled with gray 

 ones, and the faint brown shade arises from the exposed subtermi- 

 nal bands of the shorter fur which underlies the longer and coarser 

 black hairs. The under parts are darker,but otherwise resemble those 

 of the adult specimen. In the young skull the length of the upper 

 molar series is nearly as great as in the adult skulls of twice the 

 size, five millimeters longer. The incisors on the contrary, correlate 

 in size with the relative bulk of old and young, those of the latter 

 in this case being about half the caliber of the former. The sulcus 

 of the upper incisors, which characterizes this genus so strongly in 

 adults, is a nearly obsolete depression in the young and not more 

 easily detected than in occasional specimens of Microtus pennsyl- 

 vanicus which continue to exhibit this persistent index of their 



«Proc. Bos. Soc. N. Hist., 1895, p. 409. 



