440 SYSTEM A TIC SYNOPSIS. — PA SSEBES — CLAM A TOMES. 
well-turned brim, of fine fibres stuck over with lichens, the whole looking much like a nat- 
ural excrescence of the tree. Eg g s^ '^-5, creamy-white, marked with reddish-brown and 
lilac in various pattern, usually wreathing and blending about the larger end, sparser else- 
where; size about 0.75 X 0.65 — pe-d-wee ! d-pee-wee' ! 
383. C. V. rich'ardsoui. (To Sir John Richardson.) Western Wood Pewee. Similar; darker, 
more fuscous-olive above, the shading of the sides reaching almost uninterruptedly across the 
breast ; belly rather whitish than yellowish ; outer primary usually not obviously white-edged ; 
bill below oftener dusky than yellow, sometimes quite black. I fail to appreciate any reliable 
differences in size or shape ; or, in fact, any specific character. It is impracticable to pronounce 
upon a pewee, in the closet, without knowing the locality; but those familiar with both Eastern 
and Western birds in field, agree that they are not exactly the same. Note not exactly like that 
of virens; nesting said to be different {Audubon, Allen). Rocky Mountains to the Pacific; 
Labrador" {Audubon). {Tyrannula richardsonii Sw., Fn. Bor.-Am., ii, 1831, p. 146'? 
Contopus richardsonii Bd., B. N. Am., 1858, p. 189 ; Muscicapa phoebe Aud., B. Am., 8vo. ed., 
i, 1840, p. 219, pi. 61; Nutt., Man. i, 2d ed., 1840, p. 319. See Coues, B. N. W., 1874, 
p. 247.) 
123. EMPIDO'NAX. (Gr. e/x7riy, gen. e/^7ri8o9, empis, empidos, a gnat; ai/a|, anax, king. Fig. 280, d.) 
The Little Olivaceous Flycatchers. Small olivaceous species, 5.00-6.00 (rarely 6.25) 
long ; wing 3.12 or less; tail 2.75 or less; whole foot at least id as long as wing ; tarsus more 
or less obviously longer than middle toe and claw, much longer than bill ; 2d, 3d aud 4th quills 
entering into point of wing, 1st shorter or not obviously longer than 5tli ; tail not over i an inch 
shorter than wings ; breast not buffy. (Compare Sayiornis, Contopus, Mitrephanes.) As in 
allied genera, several outer primaries are slightly emarginate on the inner web, but this character 
is obscure, often inappreciable, and may be disregarded. The coronal feathers are lengthened 
and erectile, but scarcely form a true crest. There are never any more conspicuous color-marks 
than in Sayiornis fusca or Contopus virens. The bill varies with the species in size and 
shape, from almost as broad and flat as in a wood pewee in acadicus, to the narrower shape of 
a pewit in obscurus; but it is always much shorter than the tarsus. It should not be difficult 
to recognize Empidonax as different from Contopus, due attention being given to the nice points 
of diagnosis ; but it is a very difficult matter to discriminate the numerous species, requiring 
much tact, care, and patience. The following account, carefully prepared after examination of 
a great amount of material from all parts of the country, will probably suffice to determine 
ninety out of a hundred specimens ; but I confess it does not entirely satisfy me ; and, as it does 
not fully answer all the requirements of the case, it must be regarded as provisional. How 
much alike are these interesting little birds may be inferred from the fact that Wilson knew 
but a single species, acadicus, to which Audubon added but one, trailli, until Baird showed him 
two more, minimus and fiaviventris. Yet these four are perfectly distinct birds. Any experienced 
collector knows them to be different, not only when he has them in hand, but in life, by their 
haunts and habits, their notes, nests and eggs — indeed, the nests and eggs of each of them are 
readily discriminated. Three of them are common New England breeders — trailli, minimus, 
and fiaviventris; while acadicus is the common breeder in the Middle States. The case is 
complicated, however, in the West. The two exclusively Western species, hammondi and 
obscurus, are pretty distinct — entirely so from each other; but the recognition of pusillus^^ 
and especially difficilis" is somewhat conventional. Since 1858, when Baird first fixed the 
species upon anything like a satisfiictory footing, no changes whatever of his determinations 
and characterizations have been established; and as it is useless to exchange one doubtful 
opinion for another, the less obvious species may be suffered to remain as he left them. It is 
not reasonably possible to analyze all the forms in concise phrase ; the student must go at once 
to the detailed descriptions ; but the following may help him somewhat : — 
