318 ZOOLOGY. 
As the bluebird is the first to make its appearance in the spring and has 
the same partiality for a ready made domicil, the martin frequently finds 
himself anticipated and his right of possession stoutly resisted; he is, how- 
ever, generally successful, though often not without a stubborn contest. 
When forced to seek a habitation for himself, the martin selects a hollow 
tree, in which he constructs his nest, which, as is the case with most of the 
swallows, is formed principally of mud gathered from the neighboring ponds. 
The eggs are pure white. 
The other species of American swallows may all be included in the 
genus Hirundo, although otherwise arranged by some naturalists. 
The Cliff or Republican Swallow (4. lunifrons) is one of the most 
remarkable. A curious feature in the history of this bird is the fact that | 
it has spread over the Atlantic States only at a late period. It has been 
long known in the valley of the Mississippi, but has only extended itself 
eastward within fifteen or twenty years. It was not until about 1840 that 
it was known in Pennsylvania except as a rare straggler, but it has since 
then become common, and i0 some districts abundant, hundreds being 
sometimes found nesting along the eaves of a single barn, which is a 
favorite locality. The nest is built entirely of mud, and is universally 
noticed on account of its singular shape, which is similar to that of a gourd, 
with the entrance at the smaller end and curved downwards. A lining 
of grass completes it, and three to five eggs are the usual contents. 
The Barn Swallow (4. rufa) is the most common and best known 
species. The birds of this species build their nests in nearly all barns, or 
other large outhouses, in the Northern States, to which they can gain 
admittance, and it very rarely happens during the summer months that 
they are not observable in almost any landscape. This species is a great 
favorite. : 
The Swallow of Europe, H. rustica (pl. 103, fig. 7), is very similar to 
the common American species. 
Another common species is the white bellied swallow (HH. bicolor), 
though not so well known and constantly observed as the last. 
The violet green swallow (#. thalassina), a species inhabiting the 
western slope of the Rocky Mountains, is the most beautiful of the Ameri- 
can species. The bank swallow (H. riparia) derives its name from its 
predilection for streams of water, in the banks of which it excavates a hole 
and constructs its nest. The rough winged swallow (7. serripennis) has 
much the same habits, though it sometimes makes its nest in other places, 
such as the crevices in large walls, abutments of bridges, or the like. 
Sib-fam. 2. Cypseline, or Swifts. Bill less flattened than the preceding, 
longer, and with the margins inflexed and somewhat gaping. Wings very 
long, curved ; tarsi short; feet small and weak. Tarsi generally feathered ; 
tail various, sometimes forked, often truncate. Size small. 
A sub-family composed of numerous species of birds found in all parts 
of the world, and usually known as Swifts on account of their extraordinary 
rapidity of flight. The Chimney Swallow, or Swift of the United States 
(Cypselus pelasgius), is a good example of the birds of this group. It 
522 
