240 The American Naturalist. [March, 
Size of skull (average measurements of ten old adult topotypes).— 
Basilar length 23.9, Basilar length of Hensel, 22.8, zygomatic breadth 
14.7, mastoid breadth 11.8, greatest length of single half of mandible 
15.6. 
Size.—Average measurements of fifteen old adult specimens, males 
and females, from Digby, Nova Scotia, total length 167, tail vertebra 
45, hind-foot 20.3. 
Remarks.—Compared with Microtus frontigenus, M. pennsylvanicus 
acadicus is larger and much more brightly colored, and has smaller 
audital bulle.—Ourram Banas. 
A New Race of Gibb’s Mole.—In his recently published Re- 
vision of the American Moles,? Mr. F. W. True treats Gibb’s Mole, 
Neiirotrichus gibbsi (Baird), from the whole coastal strip from British 
Columbia to San Francisco Bay as one form, although he points out 
the fact that Southern examples are larger than Northern ones. I have 
long considered the species to be made up of two well-defined and easily 
recognized races, for the Southern one of which I now propose the name: 
NEUROTRICHUS gIBBSI HYACINTHINUS subsp. nov. Type from 
Nicasio, Marin Co., Cal., 9 old adult, No. 1240, Coll. of E. A. and O. 
Bangs. Collected by C. A. Allen, March 10,1894. Total length 127, 
tail vertebree 41.4, hind-foot 17.5. 
General Characters.—Size considerably larger than N. gibbsi typicus; 
color uniform black, instead of deep brownish-plumbeous as in N. gibbst 
typicus; skull larger and relatively broader. 
Color.—Black all over, with in places green and purple irridescence ; 
under fur black. 
Cranial Characters—Skull larger and relatively broader than that 
of N. gibbsi typicus. 
Size of the type skull, Basilar length (basion to front of premaxilla) 
19.8, mastoid breadth 11.4. (One of the largest skulls of N. gibbst 
typicus, from a series of eighteen from Sumas, B. C., No. 5518, Bangs 
Coll., measures: Basilar lengih 18.4, mastoid breadth 10.2.) 
Size—Averaye measurements of two adult specimens from the type 
locality: total length 123.8, tail vertebrae 39.7, hind-foot 17. (The 
average measurements of the ten largest adult specimens of N. gibbs 
typicus, from a series of eighteen from Sumas, B. C., are: total length 
116.4, tail vertebræ 38.4, hind-foot 17.4.) 
Remarks.—I am unable to say just where the two races of Gibb’s 
Mole meet ; but the San Francisco Bay specimens are very different 
2 Proceedings U. S. Nat. Mus., Vol. XIX, No. 1101. 
