446 PROCEEDINGS OF THE ACADEMY OF [May, 



witliin tlie range of 3f. americana americana above given furnish 

 martens whose average pelts are so dark as to give them a standard 

 market value much above skins from the surrounding country. 

 Such a region is the upper Nipigon territory of Ontario westward 

 toward the Lake of the Woods. The local climatic conditions of 

 this rocky, saturated and densely wooded area are responsible for 

 this. It is loo local, however, to warrant a further subdivision. 

 Respecting the cranial characters, upon which I have primarily 

 based my examinations of this perplexing group, I begin by con- 

 sidering Gray's fundamental separation of the New "World martens 

 from M. martes, foina and zlhellina on the size and shape of the 

 last upper tubercular molar. In americana this is stated by him, 

 and in measure amplified by Cones and Allen, to be different, in 

 its hour-glass shape and greater size of the inner bulb as compared 

 with the outer. In americana this tooth has but slight constriction, 

 with resulting reciangular shape, owing to the relative equality in 

 size of the inner and outer bulbs. A very careful examination of 

 the large series of American martens shows that the si)ecific separa- 

 tion from Old World forms on this basis is fully warranted. It is 

 further em ohasized by the character of the second lower true molar, 

 Avhich in all the exotic forms has a strongly characterized inner 

 cusp, as asserted by Allen. In americana, Allen says, this is " not 

 found," or " only in a very rudimentary condition. " I have found 

 it, however, in a more or less rudimentary couditiou in all typical 

 americana skulls, except those so very old that it had been worn 

 away. In rare instances this cusp is almost as well developed, pro- 

 portionately to the smaller and narrower character of americana 

 molars, as in martes. On this account its diagnostic value is less 

 than that of the last upper molar. These remarks apply equally 

 to all marten skulls I have examined taken east and north of the 

 Cascade mountains, from Nulato, Alaska, to the coast of Maine. 

 But when skulls horn, the Cascade mountain region and the Pacific 

 coast are examined an intermediate condition is immediately 

 noticeable. The shape of posterior upper molar corresponds more 

 closely to that of the Old World forms, as also does the flat, 

 rounded cranium and its broad, zygomatic width as compared with 

 its length. In these combined respects it resembles the European 

 beech marten, M. foina, more closely than it does the martens of 

 the Rocky mountains and eastern Canada. Regarding the cranial 



