We have already, while discussing1 the relations, of the Thamnophilince with the
Myotherince, adverted to that singular property, belonging to typical groups in
contiguous circles, of uniting by collateral affinity, without destroying those
circular affinities by which their own respective circles are described. We have
had proofs of this change of analogies into affinities in the families of Laniadce and
Merulidce; and we see it, if possible, more strongly exemplified in the group now
under consideration. The genus Sylmcola describes its own circle by the types
here enumerated, without the intervention of Setophaga, which is the next group,
and of equal rank. Yet the typical Sylvicolm are so beautifully connected to the
typical Setophaga, without the intervention of the aberrant forms in either group,
that it is impossible to imagine a single deficiency in the links which connect them.
We call the attention of ornithologists to this most remarkable fact, which may be
gathered from the invaluable pages of Wilson, detailing their manners, and by a
minute examination of the birds which we shall subsequently notice. The genus
SETOPHAGA, Sw.,
as being almost exclusively a North American group, may be here slightly mentioned.
As this is the Fissirostral type of the Parlance, we can feel no surprise at
its having been blended with the genuine Fly-catchers, from which it can only be
distinguished by the different structure of its wings and feet: it is represented,
among the genuine Muscicapinw, by the sub-genus Rhipidura, H. and V. The
species yet discovered are not many, and these differ in so remarkable a manner,
that the principle of their variation can never be explained or rightly understood,
without reference to the numerous affinities which this group is evidently intended
to reconcile. On one side it is to connect Sylmcola with Trichas, on another it
is to unite the Parlance with the Sylviance, and on a third it passes into Petroica.; and thus effects the union of the Parlance and the Saxicolince. It should likewise
contain species which would shew an approximation to Accentor, and thus indicate
the union of the three aberrant genera of its own sub-family. Now all these
complicated relations maybe traced in the species we already know; and yet
there is one form,—the aberrant type leading to the sub-genus Dumicola,—which
is yet undiscovered; and this, theoretically, might be supposed to be the very
one which was most essential to establish the affinity of the two genera.
We must pass over the three remaining groups of this sub-family, namely,
Trichas, Accentor, and Parus, and close our remarks with a tions on the few cursory observaSYLVIANjE,
or typical sub-family, whose circular affinities are explained by the following
genera:— Genera.
l- f Bill compressed, rather lengthened and straight, j gyfofa Auct
Typical group. \ notched; legs moderate. J
Sub-typical group.Jl { Bill shorter, more curved, nearly entire; legs long. Malurus. Vieil.* [ Prinea, Horsf.
Bill variously shaped ; hind toe stronger. 1 Hyl'iota ? Sw.
[ Culicivora, Sw.
The passage from Setophaga to the typical Gold-crested Warblers is marked
by the genus Culicivora, where one half of the bill is depressed, and the other
compressed; a singular union of the characters respectively belonging to each.
We were long in doubt as to the mode in which the aberrant circle was closed,
until our friend Dr. Horsfield very recently communicated to us a new species of
Prinea from India, having the depressed Fly-catcher-like bill of the American
Oulicivorce, with the rictus strongly bristled! On the situation of these two
genera, indeed, there can be no doubt,—the one representing the Scansores, the
other the Fissirostres; but of Hyliota we know only two specif; and until
the circular affinities of the genera immediately conterminous have been made out,
we look on this point of the series as by no means perfect.
The only material point which will detain us, as connected with the affinities of
this division, regards the genus Troglodytes. Modern naturalists generally consider
these as ScanSorial birds: not, indeed, from a partial consideration of the
solitary example found in Europe, but from looking to the general affinities and
habits of the whole group. The correctness of this opinion has more recently
been denied, upon the ground that the tongue of the Carolina Wren is like that of
a Certhia; while the tongue of the winter Wren places it with the Sylviadce.
Now, admitting this to be true; admitting also that the European Troglodytes
does not use its tongue to seize its insect food, what does the whole amount to ?
* The beautiful development of tail, seen in this group, might lead us to suspect it to be the Rasorial type of the
Sylviana ; and as its contents have not yet been analyzed, there may still be room for doubt. On the other hand, it
must be premised, that the genera, thus arranged, accurately represent the sub-families of the M erulid*-* fact
which maybe gathered by comparing this table with those at page 152. We can form no well-grounded opinion on
the precise station of the beautiful little Emu bird of Australia: its situation, either with Malwrus or Prinea, depends
entirely on the analysis of these two groups.—Sw.