i8go.] Recent Literature. 3§S 



Temm.); (9) Formicivora griseigula Lawr. , which proves to be "an 

 immature Thryothorus coraya (Gin.)"; (10) Peristera mondetoura Bon., 

 from Bogota. — R.R. 



Allen on Individual and Seasonal Variation in the Genus Elainea.* — 

 While the family Tyrannidae has been generally recognized as perhaps 

 the most difficult to study of all the large distinctively American bird 

 groups, the genus Elainea is admitted to he its most perplexing genus. 

 In working up the very extensive 'Smith Collection' of birds from Chapada, 

 Matto Grosso, Brazil, Mr. Allen found himself confronted by the not very 

 pleasant or promising task of naming a series of 129 specimens "from an 

 area of about five miles radius," representing several species, but how 

 many only the most patient investigation could determine. The chief 

 difficulty lay with specimens belonging to the pagatia-albiceps group, ot 

 which, fortunately, no less than 116 specimens were present; but this 

 richness of material for a while proved rather an embarrassment than an 

 aid. a large proportion of the specimens being "referable to the true E. 

 pagana of authors, and a still larger number to what is commonly recog- 

 nized as E. albiceps, while the great bulk of the series" was "made up of 

 specimens variously intermediate between these two forms." Mr. Allen 

 found it desirable, "in order to satisfactorily determine the relationships 

 of the puzzling birds represented in the Chapada series," to bring together 

 as much material as possible; consequently, the Elaineas of the National 

 Museum collection (numbering about 200 specimens), the Boston Society 

 of Natural History, and the Museum of Comparative Zoology in Cam- 

 bridge, were borrowed for the purpose. After patient study of this mate- 

 rial Mr. Allen was enabled to reach definite conclusions, some of which 

 were probably no less surprising to himself than to others who have read 

 his excellent paper. "The Chapada series of Elainea referable to the E. 

 pagana-albiceps group," says Mr. Allen "presents a wide range of varia- 

 tion, not only in size and coloration, but especially in the size and form 

 of the bill. Were there fewer specimens, representing the same range of 

 variation, but with most of the 'intermediates' left out, it would be quite 

 ei>v to divide the series into several apparently well-marked species, 

 and not hard to find names for them among the so-called species already 

 described. Especially would this be the case were the specimens gathered 

 from a wider geographical area, with the leading forms more or less local- 

 ized. As the case stands, however, the specimens are all from a single 

 very limited locality, and the gaps between the extreme forms are com- 

 pletely filled by specimens presenting every intermediate phase of varia- 

 tion. Besides, the variations in any other feature, — as in the form of the 

 bill, in general size, the relative length of the outer primaries, or the 

 relative length of wing to tail, — are found not to be correlated with varia- 



* Remarks on Individual and Seasonal Variation in a large series of Elainea from 

 Chapada, Matto Grosso, Brazil, with a Revision of the species of the restricted Genus 

 Elainea. Bull. Am. Mus. Nat. Hist. Vol. II, No. 3, Article XVIII, Oct. 1889, pp. 

 183-208. 



