1915.] 



INTKODUCTION. 



17 



hinder back, the old intimately mixed with the new. In an immature 

 individual of M. caligata cascadensis, taken August 5, new pelage 

 covered all of the body except the rump and tail. A somewhat 

 similar condition is shown by an adult individual of M, monax preh- 

 lorum, taken July 11, the new pelage coming in over the entire 

 upperparts, farther advanced on the fore back and shoulders. In 

 a specimen of M. Jlaviventris nosopliora, taken June 7, the molt was 

 just beginning in two patches on the hinder back. In a specimen of 

 M. f. ohscura, taken July 27, new pelage appears in the form of a 

 band on the middle of the back reaching from the top of the head 

 to the rump. (See PL II.) 



MELANISM. 



Melanism is most strongly developed in the subspecies Marmota 

 caligata vigilis. occupying the region around Glacier Bay, Alaska. In 

 this race some individuals are entirely black except for a few grayish 

 hairs on the sides and neck, and small whitish patches on the under- 

 parts and nose. No purely black specimens of M. monax have been 

 seen, but a melanistic phase is rather common in New York and 

 New England. The darkest specimen seen (from Lake George, N. Y.) 

 is dark blackish brown all over, except the head and face, which are 

 mixed mummy brown and benzo brown. Other specimens from 

 New York State are dark chestnut-brown. Vernon Bailey states that 

 he has seen a very few black individuals in Minnesota. 



A dark phase occurs also in M. Jlaviventris luteola, but this can 

 hardly be said to be melanistic (see description under that species). 

 A curious specimen of If./, avara from PuUman, Wash., has the tips 

 of the hairs of the head, fore back, and most of the underparts dark 

 blackish brown, the hirfder back being pale grayish mixed with dark 

 brown. 



MATERIAL EXAMINED AND ACKNOWLEDGMENTS. 



The present revision is based on a study of 1,051 specimens, 722 

 of which are contained in the U. S. National Museum, including 

 the Biological Survey and the Merriam collections; the remainder 

 (329 specimens) have been borrowed from other museiuns and from 

 private collections. For the loan of this material I desire to extend 

 my thanks to the following: Dr. J. A. Allen, of the American Museum 

 of Natural History; Messrs. Samuel Henshaw and Outram Bangs, of 

 the Museum of Comparative Zoology; Dr. Witmer Stone, of the 

 Academy of Natural Sciences, Philadelphia; Dr. W. J. Holland and 

 III. W. E. Clyde Todd, of the Carnegie Museum; Dr. A. G. Kuthven, 

 of the University of Michigan; Messrs. Charles B. Cory and W. H. 

 Osgood, of the Field Museum of Natural History; C. D. Bunker, 

 of the Kansas University Museum; Prof. C. C. Nutting, of the Uni- 

 versity of Iowa; ]^Ir. J. D. Figgins, of the Colorado Museum of Natural 



