BIRDS OF NORTH AND MIDDLE AMERICA. 685 
a somewhat similar nest, but with the tube more contracted below, 
out of seeds of Trizis divaricata, suspends it to a horizontal branch, 
and covers the outside with feathers; as there is no shelf on the 
inside, it is believed that the eggs are glued against the side and 
brooded on by the bird while in an upright position.¢ 
Owing to the extreme velocity of their flight and the great height 
at which they usually fly, Swifts are very difficult birds to collect, 
and consequently comparatively few species of the family are well 
represented in collections. On this account it is not easy to obtain 
a correct understanding of their geographic range and variations; 
consequently our present knowledge is, in the case of many species, 
imperfect and tentative. 
KEY TO THE GENERA OF MICROPODIDEA. 
a. Toes with the number of phalanges abnormal (2, 3, 3, 3); hallux lateral (on inner 
side of foot), capable of being directed forward (the foot then pamprodactylous), 
the inner toe sometimes reversible (capable of being directed backward), the 
toes then paired; tarsi (sometimes toes also) feathered. (Subfamily Micro- 
poding.>) 
b. Outer and middle toes directed forward, in line with axis of tarsus; feet very 
strong, the tarsi relatively shorter. 
6: DOS DakGd 232 a3 soasimemec anes ee eee Micropus (extralimital).¢ 
ce. Toes feathered. 
d. Tail slightly forked (for less than one-fourth its length), the rectrices not 
attenuated terminally; toes more sparsely feathered; feathers of pileum 
and under parts distinctly outlined, broadly rounded. 
Aéronautes (p. 687). 
dd. Tail deeply forked (for at least half its length), the lateral rectrices atten- 
uated terminally; toes more densely feathered; feathers of pileum and 
under parts blended..........-.....2.--2---2-2------ Panyptila (p. 690). 
bb. Outer and middle toes inclined outwards, at more or less of an angle with axis 
of tarsus; feet proportionately much weaker, with tarsus relatively longer. 
@ This style of nest is so different from that of the species of Chetura, whose nidifica- 
tion is known, that the proper identification of the species is very questionable. 
At the same time, it may be remarked that the suggested mode of securing the eggs 
is highly improbable. 
6 Cypselinx (not of Bonaparte, 1838) Sclater, Proc. Zool. Soc. Lond., 1865, 579; 
Carus, Handb. Zool., i, 1868-75, 253.—Micropoding Stejneger, Stand. Nat. Hist., iv, 
1885, 437, in text.—Apodinex Hartert, Das Tier., Podarg., Caprim., Macropt, 1897, 80. 
¢Apus (not Apos Scopoli, 1777, prior by anteriority) Scopoli, Intr. Nat. Hist., 
1777, 483 (type, Hirundo apus Linneus).—Micropus Meyer and Wolf, Taschenb. 
Deutschl. Vég., i, 1810, 280 (type, Hirundo apus Linneeus).—Cypselus Illiger, Prodr. 
Orn., 1811, 229 (type, Hirundo apus Linnzus).—Cipselus (emendation) Vieillot, 
Analyse, 1816, 38.—Brachypus Meyer, Vég. Liv.-u. Esthl., 1815, 142 (type, Hirundo 
apus Linneus).—Cypcelus (emendation?) D’Orbigny, Voy. Am. Mérid., iv, pt. 8, 
1839, 357. 
This genus is numerously represented in the Eastern Hemisphere, but, so far as 
known, there are only two American species, both of which belong to the southern 
continent, 
