BIRDS—IIIRUNDINIDAE—HIRUNDO. 
307 
Family IIIRUNDINIDAE. 
Sub-Family HI RUN DININAE. 
Bill triangular, very short and broad, much depressed ; the ridge much less than half the head ; the gonys two-thirds this 
jength; the gape extending to below the eye. Primaries nine; the first longest, and, with the second, considerably longer 
than the others ; the secondaries and tertials not reaching the middle of the primaries ; the secondaries deeply emarginate 
Wings very long, reaching beyond the commencement of the fork of the tail, which is generally more or less deep. Tarsi 
scutellate, very short, less than the lateral toes, the inner of which is more deeply cleft than the outer. 
The feet of the true swallows follow the general insessorial type in having three anterior toes 
and one posterior, none capable of being moved much from their normal position. This, with the 
much larger and differently shaped bill, as well as the nine primaries, instead of ten, readily 
distinguish them from the Cypselidae. 
Comparative measurements of species. 
Catal. 
No. 
Species. 
Locality. 
Sex. 
Length. 
Stretch 
of wings. 
Wing. 
Tail. 
Tarsus. 
Middle 
fts claw 
alone. 
Gill 
above. 
Along 
gape. 
Specimen 
measured. 
6019 
$ 
6.90 
5.03 
4.52 
0.44 
0 68 
0.20 
0.36 
0.62 
Drv. 
2284 
O 
4.88 
4.38 
2.20 
0.50 
0.64 
0.21 
0.26 
0.55 
Dry. 
2284 
V 
5 66 
12.25 
4.41 
2197 
3 
4.92 
2 66 
0.49 
0.63 
0.19 
0.32 
0.54 
Dry. 
2197 
6.25 
12.25 
5.00 
5494 
3 
5.00 
4.75 
2.55 
.46 
.25 
.44 
Dry. 
1895 
4.76 
4.48 
2.08 
0.46 
0.60 
0.18 
0.24 
0.50 
Dry... 
2209 
A 
4.52 
4.28 
2.23 
0.40 
0.58 
0.20 
0.28 
0.50 
Dry. 
5597 
o 
5.04 
3.9G 
2.34 
0.44 
0.62 
0.22 
0.28 
0.46 
Dry. 
1692 
V 
4.46 
3.98 
2.00 
0.41 
0.56 
0.19 
0.27 
0.44 
Drv. 
1692 
4.75 
10.83 
4.00 
1561 
3 
7.30 
5.84 
3.40 
o.co 
0.84 
0.25 
0.50 
0.92 
Dry. 
5493 
3 
7.44 
6.04 
3.66 
0.58 
0.92 
0.26 
0.52 
0.90 
Dry. 
5493 
8.25 
15.66 
5.54 
9112 
Progne chalybea?. 
Chili. 
3 
8.20 
5.48 
3.75 
0.58 
0.92 
0.25 
0.46 
0.84 
Dry. 
IllR. UNDO, Linnaeus. 
Hirundo, Linn. Syst. Nat. 1735.— Gray, Genera, I, 1845. 
Ch.—N ostrils basal, small, oblong, and covered partly by a membrane. Tail more or less forked ; the outer lateral feather 
sometimes greatly lengthened. Tarsi shorter than the middle toe, and scutellated. Tarsi naked. Toes long, slender, the 
lateral ones unequal. Claws moderate, curved, acute. 
Of this genus there are two well marked sections among the United States species—one with the 
tail excessively forked, owing to the great elongation of the lateral tail feathers; the other with 
the tail nearly square, or but slightly forked. The species will range as follows : 
Hirundo.— Tail excessively forked. 
Steel blue above; forehead and throat chestnut brown ; belly reddish white. ..H. horreorum. 
Petrochelidon.— Tail nearly even, or moderately forked. 
Tail emarginate. Forehead, throat, and rump reddish brown ; throat with a large black 
spot... ........P. lunifrons. 
Tail moderately forked. Beneath entirely white ; above opaque green ; upper tail coverts 
purple...P. thalassina. 
