108 BIOLOGICAL SOCIETY OF WASHINGTON. 



States. The smaller form, or true hyperboreus, breeds along the 

 arctic coast, from northern Alaska eastward for an undetermined 

 distance, but at least to the mouth of the McKenzie river; and 

 throughout this extent of coast-line, and thence southward over the 

 whole western portion of the continent, entirely replaces the larger 

 bird. 



As to the distinctive characters of the two races, I would remark 

 that, while the length of the wing is by no means decisive (the 

 maximum of hyperboreus being about 17.50 inches, and the mini- 

 mum of nivalis 17.00 !), nivalis always has a much larger bill, the 

 culmen in adults of this form measuring from 2.50 to 2.65, and 

 the length of the bill from tij) to point of the basal angles, 3.00 to 

 3.12, the corresponding measurements of /y'/'^;'<5<?r^«i" being only 

 1.95 to 2.28 and 2.50, or less, to 2.75. 



REMARKS ON THE TYPE SPECIMENS OF MUSCICAPA 

 FULVIFRONS, GIRAUD, AND MITREPHORUS PALLES- 

 CENS, COUES. 



By Robert Ridgway. 



(Read March 8, 1884.) 



In the " Nomenclature of North American Birds " (p. 32, Nos. 

 329 and 329«), I have included, as two races of one species, an 

 '^Empidonax fulvifrons (Giraud) Scl.," and an E. fiilvifrons pal- 

 lescens Coues. " This I did under the impression, based upon 

 previous examination of the type specimens, that they were in 

 reality sufficiently distinct to justify subspecific separation. Having 

 recently had the matter brought to mind in another connection, I 

 have re-examined the types in question, together with other mate- 

 rial, and have thereby come to the following conclusions: (i) 

 that E. pallescens is a decidedly smaller, lighter, or grayer colored 

 western race, restricted to the western side of the Rocky Moun- 

 tains, in Arizona and New Mexico, and probably portions of 

 western Mexico also, although I have not seen specimens from 



