186 VIREONIDA. 
Lanivireo), and the latter also into two (Vireo and Vireonella). The differences by 
which these sections are distinguished are given below in the headings to each group 
of species. The system here elaborated was, with slight modification, adopted in the 
‘History of North-American Birds ;’ but there, though the names Vireosylvia, Lanivireo, 
and Vireo are called subgeneric titles of Vireo, they stand at the head of each species 
with full generic rank. Dr. Coues, in his various writings, and in his most recent one 
the ‘ Birds of the Colorado Valley,’ advocates the use of Vireo in its widest sense: and 
the arguments put forward in favour of this view seem to us to be most worthy of 
consideration. One of the chief, if not the only point of distinction between Vireo and 
Vireosylvia (the presence or apparent absence of a spurious first primary) breaks down 
on close examination ; for this feather proves to be always present, though sometimes 
in a very reduced form. Moreover, in the case of V. flavifrons and V. solitarius (birds 
whose general appearance is so much alike that they have almost always been placed 
under the same generic head), the different state of development of the first primary 
in each points to their separation. 
In Vireo the legs are slender, the claws weak, and the lateral toes unequal. The 
shape of the wings varies; in some of the more migratory species they are pointed, in 
others more rounded. The bill is slender compared with such genera as Vireolanius 
and Cyclorhis, and abruptly decurved at the end as compared with Hylophilus. The 
first plumage of the young resembles that of the adult, and is destitute of spots either 
above or below. This character applies to the whole family. Twenty species are now 
known to occur within the limits of Mexico and Central America, of which nine are 
immigrants from the north during the winter season, coming in autumn and leaving 
again in spring. Of these, only two pass beyond our limits into the northern parts of 
South America. Besides these migratory birds, there are eleven more or less sedentary 
species, whereof one (V. hypochryseus) is peculiar to Western Mexico and the Tres 
Marias Islands, one (V. ochraceus) is shared by Mexico and Guatemala, one (V. pallens) 
by Nicaragua and Costa Rica, and another (V. carmiolt) by Costa Rica and Panama. 
V. huttond, a northern species, is said to be resident in Mexico: and V. amauronctus is 
also probably resident there. 
In their summer quarters the members of this genus are during the breeding-season 
cheerful songsters ; but in the winter they only utter call-notes. 
A. Ale product, acute, cauda longiores ; remex primus minutus, aliquando 
obsoletus. (Vireosylvia.) 
a. Corpus attenuatum et elongatum ; rostrum debile, angustum, rectum ; pedes debiles. 
a’. Remex spurius obsoletus. 
a". Pileus cinereus utrinque fusco marginatus. 
1. Vireo calidris, ” 
Motacilla calidris, Linn. Syst. Nat. i. p. 3297. 
