1SS7.] Dwight on a Nczv Race of Sharp-tailed S farrow. 2 7 £ 



This new form is not likely to be confounded with true cattda- 

 cutus, for, so far as my material shows, the palest streaked 

 caudacutus in any plumage may he recognized at a glance by 

 being more distinctly streaked than any specimen of stibvirga- 

 tus. More material from suitable localities will no doubt show 

 intermediates, but as yet I have seen no connecting links at this 

 end of the chain. At the other end, however, siibvirgcttus 

 passes gradually into nelsoni, as a series of fall specimens clearly 

 shows. I have been unable to obtain any spring nelsoni for com- 

 parison, but judging by the changes of plumage in the other two 

 forms, nelsoni ought to be a much blighter and more richly 

 colored bird than subvirgcttus in like plumage. This is the 

 case with fall specimens, and the points of difference arc usually 

 well defined. Compared with the new form at this season, 

 nelsoni is characterized by the rich brown of the back with white 

 edging of the feathers, instead of greenish gray with pearl-gray 

 edging; by the deeper brown of the head ; by the richer russet 

 of the wing-coverts and inner secondaries, and broader rusty edg- 

 ing of the tertials as compared with whitish or buff; by the 

 brighter orange-buff of the jugulum in sharp contrast to a whiter 

 breast and abdomen than subvirgatus shows ; by distinct (some- 

 times indistinct, however,) narrow streaks of black or dusky on 

 jugulum and sides in place of broad indistinct gray stripes; by 

 smaller size ; by a bill not over 8.4 mm., and generally by a 

 shorter wing. 



It is difficult to indicate by description differences that are 

 obvious with specimens in hand, but a preponderance of the 

 characters just given ought to determine without actual compar- 

 ison all save a few perplexing intermediates. Measurements 

 will often aid in determining these, but with a sjoecies like the 

 Sharp-tailed .Sparrow that soon wears its plumage ragged and 

 disreputable among the coarse grasses it frequents, measurements, 

 particularly of the tail, are not altogether reliable. The length o^ 

 bill in nelsoni seems to be a pretty good character, as subvirga- 

 tus (except in young of the year) seldom has as short a bill. To 

 be sure, the differences are slight but quite noticeable to the eye, 

 nevertheless. Although the largest bill of nelsoni never equals 



extent, male, 198.9 (193.-203.2) ; female, 193 (190. 5-195. 6) : wing, male, 56.1(53.9 

 57.7); female, 54.4(52.1-56.4): tail, male, 48.3 (45.5-52.1) ; female, 47.5 (44.5-50.3): 

 tarsus, 20.1 (19.1-20.8) : bill from feathers, 10.7 (10.2-11.2), from nostril, 8.1 (7.6-8.4) 

 depth at nostril, 5.1, width, 3.8. 



