598 VIOLET-GREEN SWALLOW. 
the above facts, and many equally curious, which I have mentioned, re- 
specting the variations exhibited by birds in the manner of forming their 
nests, as well as in their size, materials, and situation, it will be seen 
that differences of this kind are not of so much importance as has 
hitherto been supposed, in establishing distinctions between species 
supposed by some to be different, and by others identical. To give 
you some definite idea of what I would here impress upon your mind, 
I need only say that I have seen nests of the Barn or Chimney Swal- 
low placed within buildings, under cattle-sheds, against the sides of 
wells, and in chimneys; that while some were not more than three 
inches deep, others measured nearly nine ; while in some there was 
scarcely any grass, in others it formed nearly half of their bulk. I have 
also observed some nests of the Cliff Swallow in which the eggs had 
been deposited before the pendent neck was added, and which remain- 
ed so until the birds had reared their brood, amidst other nests fur- 
nished with a neck, which was much longer in some than in others. 
From this I have inferred that nests are formed more or less complete- 
ly, in many instances, in accordance with the necessity under which 
the bird may be of depositing its eggs. 
Hirunpo THaLassinus, Swains. Synopsis of Mexican Birds, Philos. Mag. for 1827, 
p- 365. 
Adult Male. Plate CCCLXXXV. Fig. 4. 
Bill very short, much depressed and very broad at the base, com- 
pressed toward the point, of a triangular form, with the lateral outlines 
nearly straight ; upper mandible with the dorsal line considerably con- 
vex, the sides convex toward the end, the edges sharp and overlapping, 
with a slight but distinct notch close to the deflected acute tip; lower 
mandible with the angle very broad, the dorsal line ascending and 
slightly convex, the ridge broad and a little convex at the base, narrowed 
toward the tip, which is acute. Nostrils basal, lateral oblong. 
Head rather large, roundish ; neck very short; body slender. Feet 
very small; tarsus very short, anteriorly scutellate, compressed ; toes 
free, small, the lateral equal, the first stronger: claws rather long, 
arched, much compressed, very acute. 
Plumage soft and blended, on the upper parts somewhat velvety. 
