SWIFT FOOT—S YRINX 937 
prejudiced investigator that the Cypselide not only differ far more 
from the Hirundinide than the latter do from any other Family of 
Passeres, but that they belong to what in the present state of 
ornithology must be deemed a distinct Order of Birds—that which 
in the present work has been called Picariz. That the relations of 
the Cypselidex to the Trochilide (HUMMING-BIRD, pp. 442, 443) are 
close, as has been asserted by L’Herminier, Nitzsch, Burmeister and 
Prof. Huxley, is denied by Dr. Shufeldt (Proc. Zool. Soc. 1885, pp. 
886-914 ; Ibis, 1893, pp. 84-100), but the views of the last are con- 
troverted by Mr. Lucas (Auk, 1886, pp. 444-451; Ibis, 1893, pp. 
365-371). ; 
SWIFT FOOT, Selby’s name in 1825 (Brit. Orn. i. p. 334) for 
what was already known as the CouRSER (p. 107). 
SWINEPIPE, an old name for the REpwinc, Turdus iliacus 
(p. 777, note 1). 
SYNALLAXIS, the name of a genus instituted in 1819 by 
Vieillot (NV. Dict. dH. N. xxxii. p. 309), and used as English in 
1825 by Stephens (Shaw’s Zool. xiii. p. 227) (cf. PicucuLs, p. 719). 
SYNDACTYLI, one of Illiger’s groups of SCANSORES (p. 815) 
in 1811 (Prodr. Syst. p. 207) consisting only of the genus Galbula 
(JACAMAR, p. 463). 
SYRINX, the organ of voice, and a peculiarity of the class 
AVES, in so far as it is a modification of the lower end of the 
TRACHEA and adjoining parts of the Broncul (p. 58), whence it is 
frequently called the Lower Larynx (p. 513). The essential 
features of such an organ are, first, membranes stretched between 
the several parts of a cartilaginous or bony framework, and next, 
special muscles which by their action vary and regulate the tension 
of the membranes. 
In the majority of Birds the median wall of each bronchial 
tube is formed by a membrana tympaniformis interna, while a variable 
number of membranz tympaniformes externe exist on the outer side, 
either between neighbouring bronchial semirings, or between the 
first bronchial semiring and the last tracheal ring, or between the 
last two tracheal rings. ‘The two inner tympaniform membranes 
mostly meet at the pessulus (p. 58), whence they often extend into 
the lower end of the Trachea as a semilunar fold. When there is 
no pessulus these two membranes meet directly and are attached to 
the ventral and dorsal corners of the last tracheal ring or rings. 
The position of the bronchidesmus (p. 58) varies considerably. In 
Anseres it lies very near the pessulus, and is easily overlooked, while 
in Galline it is placed further back and is very conspicuous: in 
Ardea, Buteo, Cuculus and Cypselus it is situated at the 5th pair of 
bronchial semirings, but at the 8th in Picus and Podicipes. 
All the muscles of the Syrinx (grouped as B. £. at p. 605) are 
