98 EXTINCT AND VANISHING MAMMALS 



This meadow mouse is an island race of the common Micro- 

 tus pennsylvanicus of eastern United States, from which it 

 differs only in minor characters. At the present time it is 

 believed to be extinct. 



Bailey describes this as darker than typical M . pennsylvani- 

 cus, the upper parts dark yellowish bister, heavily mixed with 

 black hairs, darkest on nose and face; belly dusky, washed 

 with cinnamon; feet blackish; tail blackish above, dark brown 

 below. The skull is characterized by its shorter, wider brain 

 case and its wider and more abruptly spreading zygomatic 

 arches. In the last upper molar the anterior inner and outer 

 triangles are confluent and nearly opposite instead of being 

 separated by enamel walls. Basal length of skull, 26 mm.; 

 zygomatic breadth, 16.2. 



Beyond the original and supplementary descriptions of this 

 meadow mouse by Bailey (1900, p. 26), nothing seems to be 

 known of it. That author remarks: "Microtus nesophilus 

 needs no comparison with breweri or terraenovae, the other two 

 insular forms from the Atlantic coast. In general appearance 

 it more nearly resembles pennsylvanicus, but in cranial char- 

 acters it is as distinctly different as either of the other island 

 species. During the month of August, 1898, Mr. A. H. Howell 

 visited Great Gull Island for the purpose of getting specimens 

 of Microtus, but he found their old haunts covered by the 

 earth moved in grading the island for fortifications, while no 

 trace of the animals remained. He thinks they are completely 

 exterminated." Fifteen specimens are listed in the collection 

 of the United States Fish and Wildlife Service, but apart from 

 these and Bailey's account there seems to be no further record 

 of the race. It is a good example of the precariousness of the 

 status of an island form, which with some unusual modification 

 of its habitat is exposed to new dangers, 



Since Bailey's account of this race (for such it may best be 

 considered), the meadow-mouse of Block Island, R. I., has 

 been described as an insular race by Bangs (1908, p. 20) under 

 the name Microtus provectus. The differential characters seem 

 slight but perhaps sufficient to warrant this action. There is 

 nothing to indicate that it is in any present danger, though 

 conceivably changing conditions on Block Island might alter 

 its habitat sufficiently to imperil it. Of the supposed race M. 

 pennsylvanicus shattucki Howe, of Tumbledown Dick Island, 



