TURDIDJE — TUBDINJE : THRUSHES. 
241 
lid(E and Sylviidce), between which and TurdidcB, however, no line whatever can be drawn. 
Tlie vast assemblage of Old World Warblers are in fact much more thoroughly Thrush-like 
than are our Mimincc, for example ; and the Turdidce would be much more homogeneous and 
easy to characterize if the Mock-birds and Gnat-catchers, with scutellate tarsi and not strictly 
spm-ious 1st primary, were to be excluded. The relationships of the Mimince with the Wrens 
are really so close, that they have often been associated with the Troglodytidce, to which they 
would probably be best assigned after all. The position of Polioptila is uncertain ; but it 
cannot well go with ParidcB, and does not seem to be very different from some of the Sylvine 
forms now brought under Turdidce. 
The North American members of the Turdidce offer collectively the following characters : — 
Wing of ten primaries, of which the 1st is spurious or quite short — attaining functional 
size only in Mimince and Polioptilince. Wing more or less elongate and pointed, longer than 
the tail (shorter and more rounded in Poliopttla and most Mimince'). Inner secondaries never 
long and flowing 
Motacillidce. Bill never stout and conical, nor with angulated commis- 
sure, nor flattened with gape reaching under tke eyes ; usually slender, straight or little curved, 
more or less compressed, subulate and acute, usually notched at end of upper mandible (but 
the nick frequently 
obsolete, and whole 
bill attaining ex- 
traordinary charac- 
ters in Harporhyn- 
chiis). Nostrils oval 
or roundish, rarely 
linear, exposed in 
conspicuous nasal 
fossae ; nearly or 
quite reached or 
overreached by the 
frontal feathers, but 
never concealed by 
a dense ruff as in 
Paridce and Sittidce. 
Rictus bristled or 
with bristle-tipped 
feathers, except in Cinclus. Tarsus normally booted, the anterior scutella, excepting a few 
below, being fused in a continuous plate, — not so in Mimince and Polioptilince. On the sides 
and behind, tarsus strictly lamini plantar (compare Alaudidce and some Troglodytidce) . Tarsus 
usually also long and slender; never decidedly shorter than the middle toe and claw, often 
decidedly longer. Anterior toes deeply cleft, the inner to its very base, the outer adherent to 
the middle for only the length of its basal joint (compare Troglodytidce). Hind claw never 
lengthened and straightened as usual in Motacillidce. Tail feathers twelve; tail normally 
much shorter than the wings, sometimes about equal, only decidedly longer in some Mimince ; 
never cuneate, nor deeply forked, nor doubly rounded. 
Any North American bird showing bf)oted tarsi, ten primaries, the 1st spurious, — and 
not double-rounded tail — is one of the Turdidce. The group thus constituted is divisible 
into several sub-famiUes, which may be analyzed as follows with reference to the North Amer- 
ican genera : — 
Analysis of Subfamilies. 
TuRDiN^ : Typical Thrushes. Tarsi booted. Rictus bristly. Nostrils oval, exposed. 
BiU straight, shorter than head. First quill strictly spurious ; 2d between 4th and Gth. Tail 
16 
B 
Fig. 114. — Skulls of Turdidce and SylvicoUdce, nat. size; after Sbufeldt. A, Oro- 
scoptes montanus ; B, Sialia viexicana ; C, Cinclus mexicanus ; D, Siurus naivius. 
Observe likeness between A and B, at points marked c, c^, I, U ; and between C and D, 
at points marked h, 6/ d, d^. 
