1885.] PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 579 



decidedly smaller, and with the thighs aud under wing-coverts nearly or 

 quite immaculate, instead of distinctly barred and spotted, respectively. 

 Wing, 8.00-8.80 (average of the specimens, 8.44) ; tail, G.00-G.30 (ave- 

 rage, C.13) ; culmen, .00-72 (average, .67) ; tarsus, 2.20-2,40 (average, 

 2.33); middle toe, 1.05-1.20 (average, 1.17). 



3Iale, nearly adult (type, No. 102,852, Cozumel, January 27, 1885): 

 Upper parts nearly uuiform grayish brown, the feathers with dusky shafts, 

 and those of the dorsal region and wings with very narrow and rather 

 indistinct paler margins, especially terminally ; longer upper tail-coverts 

 bufl', or pale ochraceous, marked with sharply defined transverse, nearly 

 reniform, spots of umber brown. Tail deep brownish gray, crossed by 4 

 bands of black, averaging about .50 of an inch wide, or nearly as wide as 

 the brownish gray interspaces; the width gradually decreasing, however, 

 from the last, or subterminal one, which is succeeded by a narrower 



races are (1) the true magnirostris, from South America north of the Amazon ; (2) As- 

 turina nattereri, Scl. & Salv., from Brazil and eastern Peru ; (3) Asturina ruficauda, 

 SCL. & Salv., from Central America (Isthmus of Panama to Nicarajjua); (4) Rupor- 

 nis magnirostris griseocauda, Ridgw., from southern Mexico and Guatemala, and (5) 

 B. magnirostris gracilis, an insular form from the Island of Cozumel. To these it may 

 hereafter prove necessary to add (6) Asturina pucherani, Yerr., from the Argentine Re- 

 public, aud (7) A. saturata, Scl. & Salv., from Bolivia. lutergradation between two 

 of the above named forms has been proven in two instances, viz., between magniros- 

 tris and nattereri aud between ruficauda and griseocauda, respectively ; and in the case 

 of the others, the relationship is so close that intergradatiou may safely be assumed. 

 A. saturata apparently connects nattereri with puclierani, or at least has resemblances 

 to both. Some authors have refused to recognize the validity of the form M'hich I 

 have named griseocauda, on the ground that intermediate specimens connect it with 

 ruficauda; but in so ruling they utterly ignore the very distinction between species 

 and geographical races, i. e., the fact of intergradatiou in the case of the latter. Giv- 

 ing this distinction due consideration, it is found that griseocauda is just as well 

 marked a race as any of the forms which have usually been ranked good species, but 

 the circumstance that ruficauda and griseocauda are better represented, both numeri- 

 cally and as to locality, in collections than are the others, and that intermediate speci- 

 mens are consequently more numerous, has rendered its distinctness less apparent. 



The National Museum collection contains 23 adult specimens of ruficauda aud griseo- 

 cauda together ; and the way in which the two forms intergrade, as shown by this 

 series, is as follows : 



Panama (1 specimen). — Tail-bauds rufous. 



Chiriqui{l specimen). — Tail-bauds rufous. 



Costa Rica (8 specimens). — Tail-bands rufous in 4, chiefly rufous in 3, and gray 

 mixed with rufous in 1. 



Nicaragua (5 specimens). — Tail-bands with rufous predominating in 1, with gray 

 predominating in 4. 



Guatemala (1 specimen). —Tail-bands gray, but much tinged with rufous, especially 

 on lateral feathers. 



Yucatan (.S specimens). — Tail-bands gray in all ; in 3 of them, the basal portion of 

 the outer web of lateral rectrices mottled with pale ochraceous, and iu 2 others the 

 same portions tinged with rvifons. 



Tehuantepec (1 specimen). — Tail-bands gray, the outer web of lateral rectrices tinged 

 with rufous at base. 



Vera Cruz (1 specimen, from Mirador). — Tail-bands gray, the basal portion of the 

 rectrices (except middle pair) tinged with rufous. 



