MOTACILLID^: WAGTAILS AND PIPITS. 
283 
Primaries 10, the spurious 1st primary minute but evident. Head subcrested, but without 
lateral ear-tufts. Wings long, pointed, the tip formed by the first 3 developed primaries ; 
inner secondaries long and flowing. Tail emarginate, little more than half as long as wing. 
Tarsus equal to middle toe and claw. Lateral toes of unequal lengths. Sexes alike. Nest on 
the ground. Eggs 4-5, thickly speckled. 
A. arven'sis. (Lat. arvensis, relating to arable land; arvum, a ploughed field.) Sky Lark. 
Upper parts grayish -browm, the feathers with darker centres; under parts whitish, tinged 
with buff across breast and along sides, and there streaked with dusky ; a pale superciliary 
line ; wings with much whitish edging ; outer tail-feather mostly white, the next one or two 
with white borders. Length of ^ 7.50; extent 14.75; wing about 4.00; tail 2.50; bill 
0.50; tarsus or middle toe and claw 1.00; hind toe 0.45, its claw up to nearly 1.00. 9 
smaller. This celebrated bird, whose music so often inspires the poet, occurs as a straggler 
from Europe in Greenland, and also, it is said, in Bermuda and Alaska. It has also been im- 
ported and turned out in this country, where it may perhaps become naturalized. 
8. Family MOTACILLID^ : Wagtails and Pipits. 
Bill shorter than the head, very 
slender, straight, acute, notched at 
tip. Nostrils not concealed by 
feathers, which however reach into 
the nasal fossae. Rictus not nota 
bly bristled. Primaries 9, of which 
the 1st is about as long as the 2d, 
and the first 3, 4, or 5, form the 
point ; inner secondaries enlarged, 
the longest one nearly or quite 
equalling the primaries in the closed 
wing. Tail lengthened, averaging 
about equal to the wing. Feet 
long and slender ; tarsus scutellate, 
usually longer than the middle toe 
and claw ; inner toe cleft to the 
very base, but basal joint of outer 
toe soldered with the middle one ; 
hind toe bearing a long and little 
curved claw (except in Motacilla 
proper). A pretty well-defined 
group of one hundred, chiefly Old 
World, species, which may be 
Fig. 156. -Upper, White Wagtail; lower, Yellow Wagtail. ^^rmed terrestrial Sylvias, all liv- 
(From Dixon.) . ing mostly on the ground, where 
they run with facility, never hopping like most Oscines. They are usually gregarious ; are 
insectivorous and migratory. They have gained their name from the characteristic habit of 
moving the tail with a peculiar see-saw motion, as if they were using it to balance themselves 
upon unsteady footing. They may be distinguished from all the foregoing birds, except 
Alaudida, by having only 9 primaries ; from all the following Oscines, by having long flowing 
inner secondaries ; and from Alaiididm, with which they agree in this respect, as well as in 
usually having a lengthened, straightish hind claw, by having the tarsal envelope as in 
Oscines generally, slender biU, and exposed nostrils. Two subfamilies are generally recog- 
nized, though the distinctions are scarcely more than generic. 
