peice «Z.C., VOL. 1V PLATE 
Microtus breweri Microtus provectus Microtus pennsylvanicus 
Muskeget Isd., Mass. Block Island, R. I. Wareham, Mass. 
No. 727 No. 9794 (type) No. 5415 
SKULLS OF MICROTUS BREWERI, MICROTUS PROVECTUS AND MICROTUS PENNSYLVANICUS 
About 14 natural size 
