NORTHERN ZOOLOGY.
DESCRIPTION
Of an immature bird from Hudson’s Bay, now in the British Museum.
C olour of the head white, with longitudinal brown streaks. The feathers on the dorsal
aspect of the body have hair-brown centres, with white borders, and also an oval spot on each
web indented into the brown. The tail feathers have brown shafts ; in the two outer feathers
the brown encroaches on the webs, and in the two middle ones there are also six or seven
irregular brown blotches. The breast and belly have elliptical brown marks in the centres of
the feathers.. In other respects, and in the acute tooth on the upper mandible, the specimen
resembles the mature one above described.
Dimensions.
' ' - Inches, lines.Length (total) . . .2 2 6 ’ Length of the largest quill feather . ■/ . ,I n1c4h es. Lin0es. . „ of the tail'' . . . . 8 0 „ o f the tarsus . , . 2 4
The Falco sacer of Forster;, sent from Hudson’s Bay, and described in thé
Philosophical Transactions, is a still younger bird than the preceding, probably a
yearling.
Its upper plumage was dark brown, with pale reddish-brown margins and spots on the
webs, which did not reach the shafts. The quill feathers were brownish-black, with white
tips and edges, round rust-coloured spots on the outer webs, and transverse bars of the same
colour on the inner webs. The tail was dark brown, with a white tip, and crossed by about
twelve white bauds. The head and whole under surface were white, with longitudinal brown
marks. Cere and feet bluish. Iris yellow. Its length was 22 inches; its extent 36 inches,
and its weight 2i lbs.
The description of Edwards’s Ash-coloure/l Buzzard corresponds" nearly with1 Forster’s,
but the colouring of his figure is indifferent.—R.
The remarkable variation in the form of the bill, before alluded to, - deserves
attention ; since naturalists have given no elucidation of a fact so curious. It has,
indeed, been surmised, that two species may possibly exist in our museums under
this name; but on this point we can offer no opinion. Several instances, however,
might be named, where the variation in the bills of individuals (unquestionably
of the same species) is fully as great as in. the present instance. This fact
may be accounted for in two ways; first, from the effect of age, the young not
having the full development of that structure which is typical of the adult; thus,
in the youngest specimen of the American Harrier, subsequently described, the
cutting margin of the upper mandible is straight, while in the older specimens this
margin is strongly sinuated. Secondly, by that wonderful regularity in the progression
of natural affinities, which is not only apparent in species, but even in the mode
o f variation o f those species. Sometimes these resemblances indicate analogies,