NO. 1101. rBOCEEDINGS OF THE NATIONAL MUSEUM. 105 



An old individual (probably a male) from Sumas, British Columbia, 

 taken Ajnil 19, has the new fur concealed under the old over the whole 

 body. Another old male from the same locality, taken April 20, has 

 an isolated area of short fur qn the back of the neck, but I am in doubt 

 as to whether this is a genuine evidence of molting. The series from 

 Sumas comprises tliiity-four si^ecimens with dates from April 12 to 

 June 21, bnt 1 have been unable to find any evidences of molting other 

 tlian those mentioned. From this I can only suppose that the change, 

 except in very old individuals, does not begin earlier than the last 

 week in June at the northern limit of the range of the species. 



A larger number of specimens were taken in spring and several of 

 these are molting. One is from Lake Cushman, Washington (a male), 

 taken June 23, and has entire new fur, except a small area above the 

 base of the tail and another on the right flank. Two other males 

 taken at the same place, June 21 and June 27, respectively, appear to 

 have completed or practically completed the molt. From these speci- 

 mens it would appear tliat the spring molt in this northern locality is 

 not ordinarily completed until the latter i)art of June. It is earlier 

 further south. 



A specimen (male) from Carberry's Eancli, California, on the Sierra 

 Nevadas, taken May 23, has nearly completed the molt, having the old 

 Ihr only on the posterior half of the back. Two others from the same 

 locality (one known to be a male) taken May 22 and 18, respectively, 

 api)ear to have completely changed. From this material it is probable 

 that the molt is complete at this point in all ordinary cases prior to 

 the 1st of June. 



In Oregon, as might be expected, the change seems to take place at 

 a i)eriod intermediate between those of the Washington and California 

 specimens. A male taken June 8 at Siskiyou, Oregon, appears to have 

 new fur entirely. 



])ES(!RlPTION OF THE TV1>E SPECIMEN OF NEi'ROTRK^HUS GIUUSII 



(BAIRD). 



The type of the species is IS'o. -/l^^^^, U.S.N.IM. It was collected by 

 Dr. Suckley in July, 1851, in the White River Pass, north of Mount 

 Eaiuier, Washington. It is aj'ouug individual, as is shown by its size, 

 and by the fact that some of the milk teeth are still retained. The skin 

 appears to be somewhat faded, but is otherwise in good condition, but 

 the skull is badly broken and incomplete. 



The head and !)ody measured on the skin are .")(».,"» mm.; the tail ver- 

 tebrte, .")3 mm., and the hind foot (without the claw), 12.4 mm. 



The skull, as already stated, retains the majority of the milk teeth. 

 The milk incisors and canine are small unicus])idate single-rooted teeth. 

 The second upper milk premolar is a large two-rooted tooth, of the 

 same triangular form as its permanent successor. The first |)remolar 

 is smaller, but still as large as the peruianent one, and like it also two- 

 rooted. 



