THYMUS GLAND—TICHICRO 961 
The Thrushes have been generally considered to form a distinct 
Family, Zurdidx, which is placed by some taxonomers the highest 
in rank among birds. The fallacy of this last view is pointed out 
elsewhere (INTRODUCTION). Though many modern systematists will 
admit the close connexion of the 7'urdidx and some of the so-called 
Family Sylvide (WARBLER), the abolition or modification of the 
latter, by wholly or partially merging it in the former, has not yet 
been satisfactorily effected. Mr. Seebohm (Cai. B. Br. Mus. v. p. 
1), being compelled by the conditions previously laid down by Dr. 
Sharpe (op. cit. iv. pp. 6, 7) to unite them, protested against doing 
so. His own assignment of the subfamily Turdinw was into li 
genera, of which, however, 6 only would be commonly called 
Thrushes, and it must be borne in mind that in establishing these 
he regarded coloration as the most valid character. They are Geo- 
cichla (a phantom name) with 40 species, Zurdus with 48, Merula 
with 52, Mimocichla with 3, Catharus with 12 and Monticola with 
10. These last, well known as Rock-Thrushes, make a very near 
approach to the RepsTart (p. 775) and WHEATEAR. 
THYMUS GLAND, a body of obscure significance; but 
wrongly called a gland. It is best developed in young birds, and is 
a yellowish mass extending on either side from each bronchus along 
the jugular vein and ending like a thread. In adults it becomes 
much reduced and is not unfrequently lost. 
THYREOID GLAND, like the last, is of unknown function 
and wrongly called a gland. It is a small, oval, reddish-yellow 
body situated on either side of the root of the neck, loosely covered 
by the skin and attached to the carotid artery and jugular vein. 
In an adult Swan it is about three-quarters of an inch long. 
TIBIA, in common descriptive ornithology the third and 
generally the longest portion of the Bird’s leg, intervening between 
- the Femur and the so-called “Tarsus.” For its actual composite 
nature see SKELETON (p. 863). 
TICHICRO, the name (given from its note) in Jamaica of a 
small bird, the Fringilla savannarum of Gmelin, now referred either 
to the genus Coturniculus, of which the very closely allied /’. passerina 
of Wilson, the Yellow-winged Bunting of North America, is the type, 
or to Ammodromus, founded for the Sharp-tailed Finch, 4. caudacutus. 
Both belong to a group of New-World forms hitherto ill defined, 
and considered by some to be FINCHES and by others BUNTINGS. 
Of somewhat Lark-like habit, the Tichicro is said by Gosse (b. 
Jam. p. 245) to have the habit of running on the ground, and to 
perch but seldom, in which respect it differs from both normal 
Finches and Buntings (c/. TOWHEE). 
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