These objections have had their due weight, and they suspended our judgment
on this matter for some time. The first, indeed, is só strong, that if our
views on the Insessores are correct, it can only be accounted for by that property
which may belong to typical groups, adverted to in our introductory remarks; that
is, of gradually approximating, in proportion as we contract our views, from order
to family, from family to sub-family, and from sub-family to genus: so that, in
cases where every conceivable intervening form is known, what was in larger
groups but a relation of analogy, finally becomes one of absolute collateral
affinity; a relation, however, which by no means disturbs the true or direct affinity
by which each of these groups revolve, and are united in their own proper circles.
An instance of the same intimate relationship may bè cited between the true
Merula; and the Nightingale-warblers (Philomelince'), in the family of Sylviadw ; two
groups, whose juxta-position is precisely the same as Thamnophüus and Myothera,
and which, in like manner, evince so close a resemblance, that the Sylvia
turdoïdes of M. Temminck is described, in the first edition of that author’s valuable
work on the Birds of Europe, as a true Turdus, under the name of Turdus arun-
dinaceus ; in which genus it has also been placed by Dr. Latham and others.
Here, then, is a case in point, where the analogy between the corresponding points
of two family circles is so close, as to amount to what we should be justified in
calling, under other circumstances, an absolute and direct affinity. That such, however,
is not the case in regard to the Sylvia turdoïdes, as connecting the Merulidce
with the Sylviadw, will subsequently appear; and, in respect to the supposed
affinity between the Pipra pileata and the sub-genus Prionops, the evidence to
be adduced is much more in favour of their direct analogy.
We shall close these remarks—already extended, perhaps, to too great a
length—with a hope that they may awaken the attention of ornithologists to these
singular relations between the Thamnophilinw and the Myotherince ; not so much to
elucidate the groups themselves, as to investigate whether the typical circles, in
small assemblages of natural objects, do not insensibly acquire additional properties
beyond those which are possessed by larger groups. The only writer in whose
works we can trace any opinion on this intricate subject, or who appears to have
given an intimation that analogies may blend into affinities, is our friend
Mr. Haworth, who, in his new binary arrangement of the Macrurous Crustacea {Phil.
Mag.), makes the following observation : “ The first articles of every dichotomy
are often merely analogies ; but that these insensibly, as we go down the table,
to arrive at the genera, lessen, and blend into the closest affinities.” Whether this
passage, however, can be cited as strengthening our own suspicions, we cannot
well make out, as its author has not yet fully developed his views of natural
arrTahneg eomtheenrt .forms which appear to enter among the Thamnophilinw are Colluri-
■ cincla (H. andV.), Tephrodornis (Sw.)? and Prionops (Vieil.) Of the first we can
say nothing, further than it appears to bear the same relation to ThamnophUus as
Laniellus, Sw. , does to I m M u s . It is in Tephrodornis that we first detect an evident
reduction in the length, size, and power of the tarsi. The wings, which have hitherto
been remarkably short and feeble, are now more lengthened and obtusely pointed;
while the tail, firm and strong, is either perfectly square, or slightly emarginate.
Besides these indications of a new set of characters, we perceive the frontal
feathers somewhat lengthened, arid reflected over the .nostrils, and the base o f the
bill, which they protect and partially cover; the rictus, also, is very strongly
bristled. All these characters deserve attention, not only as showing an affinity to
Prionops, .but as being the first development of that structure so fully exemplified
in the Edolianw. .
Tephrodornis is. still more interesting, as containing several small species,
found in the Indian islands; one of which we strongly suspect is the Muscicapa
hirundinacea of Reinwaldt, which, but for its size, would unquestionably have
been long ago referred to this family. The bill exhibits the same formation as
that of Lanius virgatus, Tern., but on a very small scale, and has not the least depression,.
except at its base. This little bird is not much larger than the smallest
Formicivora yet discovered; but we are unacquainted with any form by which the
two groups are connected. In Prionops, the feet are also weak, the tail nearly
square, and the wings still more lengthened, broad, and ample. This curious
bird is said to frequent the ground; and should it eventually prove an annectant
form between this and the next sub-family, we have another proof of that remarkable
partiality which Nature appears to evince, of making her transitions from
one family to another by means of groups strictly terrestrial.
The bill of Prionops is fully as slender as that of Colluricincla; while the similarity
of this type to Platylophus in the structure of the feet, the rictus, the frontal
feathers, &c., sufficiently indicates in what manner the aberrant forms of the
Thamnophilinw are united in a circle o f their own. Whether we regard Tephrodornis
as the last genus in this division, or as the first in the next, its affinity to
both is unquestionable, and we may therefore at once proceed to the sub-family,