TROCHILID^—mOCHILINJE: HUMMING-BIBDS. 459 
from the fact that, as in Passeres proper, the flexor longus hallucis is independent of the flexor 
longus digitorum, — that is, the muscle which bends the hind toe M^orks separately from that 
which flexes the other toes collectively. The arrangement of the thigh muscles is the same as 
in CypselidcB. There is one carotid artery, the left ; a nude oil-gland ; no coeca. The pterylosis 
is characteristic. 
The food of the Hummers was formerly supposed to be the sweets of flowers. It is now 
known that they are chiefly insectivorous. Their little nests are models of architectural beauty. 
The eggs are always two in number. The young hatch weak and helpless, requiring to be fed 
by the parents, the Hummers being thus of altricial nature. The voice is not musical. 
The family is one of the most perfectly circumscribed in ornithology, and one of the largest 
of its grade. So intimately and variously are the genera interrelated that every attempt to 
divide it into subfamilies has proven unsatisfactory. The hummers are peculiar to America. 
Species occur from Alaska to Patagonia ; but we have a mere sprinkling in this country. The 
centre of abundance is in 
tropical South America, 
particularly New Gra- 
nada. Nearly 500 spe- 
cies are current; the 
number of positively spe- 
cific forms may be esti- 
mated at about 400 or 
more. The genera or 
subgenera vary with au- 
thors from 50 to 150. 
The latest critical author- 
ity upon the subject gives 
426 species, assigned to 
125 genera. (Elliot.) 
None of the known 
N. A. Hummers exhibits 
the extremes of shape of 
bill or tail which some of 
the tropical genera illus- 
■ trate ; in only one {Calo- (Sheppard del. Nichols sc.) 
thorax lucifer) is the bill decidedly curved. Only one species is as much as 4 inches long, — 
the magnificent Eugenes fulgens. Some curious shapes of tail, including marked sexual 
characters in this respect, are exhibited by certain genera. 
Only one species, the common Ruby-throat, is known to occur in the East ; this was the 
only one known to Wilson. Audubon gave four species, but one of them erroneously. Since 
his time, however, new forms of these exquisite creatures have successively been brought to 
light over our Mexican border. In 1858, Baird gave seven (one of them Lamj^ornis mango, 
erroneously, as Audubon had done). In 1872, in the Key," I was able to increase the number 
to ten, but with two wrongly given (the Lampornis and Agyrtria linncei). The same ten, with 
the two errors, w'ere given by Baird and Eidgwayin 1874. Within a few years the discoveries 
have been so many, that, after eliminating the two errors, I am able to describe no fewer than 
fifteen perfectly distinct species of United States Humming-birds ; and I have no doubt that 
several others will in due time be found over our Mexican border. 
The discrimination of the females and young is difficult ; but wdth the adult males there 
should be no trouble. The following table is intended to enable the student to tell the genus 
and species directly of any U. S. Hummer, if the specimen he has in hand be an adult male. 
Fig. 299. — Ruby-tliroated Humming-birds, J*, $, and nest, nearly nat. size. 
