TURBID^ — TURBINE : THRUSHES. 



241 



lido: and SylviicUE), between which and Turdidce, however, no line whatever can be drawn. 

 The vast assenibhige of Old World Warblers are in fact much more thoroughly Thrush-like 

 than are our Mimince, 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 

 spurious 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 Paridce, and does not seem to be very different from some of the Sylvine 

 forms now brought under Turdidce. 



Tlie 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 ixi Mimince and Polioptilince. Wing more or less elongate and pointed, longer than 

 the tail (shorter and more rounded in Polioptila and most Mimince). Inner secondaries never 

 long and flowing as in Motacillidce. Bill never stout and conical, nor with angulated commis- 

 sure, nor flattened with gape reaching under the eyes ; usually slender, straight or little curved, 

 more or less compressed, subulate and acute, usually notched at end of upper mandible (but 

 the nick ft-equently 

 obsolete, and whole 

 bill attaining ex- 

 traordinary charac- 

 ters in Harporhyn- 

 chus). 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 seutella, excepting a few 

 below, being fused in a continuous plate, — not so in Mimince and Polioptilince. On the sides 

 and behind, tarsus strictly lainini 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 booted 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-families, which may be analyzed as follows with reference to the North Amer- 

 ican genera : — 



Analysis of Subfamilies. 



TuRuiN.^ : Typical Thrushes. Tarsi booted. Rictus bristly. Nostrils oval, exposed. 

 Bill straight, shorter than head. First quill strictly spurious ; 2d between 4th and 6th. Tail 



16 



A B C 



Fig. 114. — Skulls of Turdidce and SylvicoUdcB, nat. size; after Shufeldt. A, Oro- 

 scoptes montanuf: ; B, Sialia mexicana ; C, Cinclus mexicanus ; D, Siurus ncevius. 

 Observe likeness between A and B, at points marked c, c', I, l' ; and between C and D, 

 at points marked b, h/ d, d' . 



