THE IVORY-BILLED WOODPECKER. 
225 
hyoid bones, and the action of another pair of muscles, to be presently 
described. 
The tongue, d, is covered externally with a dense sheath of fibrous tissue. 
On its lower surface is seen on each side a very slender muscle, commencing 
at the extremity of the glosso-hyal bone, and running along the whole length 
of the basi-hyal bone, as well as of the apo-hyal, to be inserted into the 
cerato-hyal, at the distance of one inch from its base, on the outer edge. 
The action of this muscle, which has a strong tendon in its whole length, is 
to bend the tip of the tongue downwards, or to move the horn of the hyoid 
bone outwards. It may be called the glosso-hyal. It has another tendon 
running parallel to that mentioned, along its upper edge, of which the action 
must be to bend the tongue upwards upon the apo-hyal. Besides these 
muscles, there is another pair, forming a greater part of the fleshy portion 
of the tongue. They commence at the tip of the basi-hyal bone, or at d, 
proceed along the upper surface of the tongue, and, after running a course of 
21 inches, pass along the anterior surface of the thyroid bone, wind along 
its edge, and are inserted near the middle surface of the trachea, about its 
tenth ring. The action of these muscles, alluded to at the end of the last 
paragraph, and marked n n, is to retract the tongue, when extended, as well 
as to pull forward the larynx. 
Another pair of very slender muscles, m m, commence upon the edge of 
the thyroid bone externally of those last described, separate immediately 
from the trachea, pass directly down the neck in front, under the subcuta- 
neous muscle and skin, to which they are firmly attached by cellular tissue, 
and are inserted into the furcular bone about the middle of.its length. These 
muscles, the cleido-tracheales, are not peculiar to Woodpeckers, and have 
nothing particular to do with the movements of the tongue in those birds. 
Parallel to the lower edge of the jaw, and extending from 4 twelfths 
anteriorly to its articulation to the junction of its crura, is, on each side, an 
elongated salivary gland, //, attached to the jaw by cellular tissue. It is of 
a yellowish colour, internally parenchymatous, and sends off a duct, which 
enters the mouth by the aperture already mentioned, at the commencement 
of the groove in the horny part of the lower mandible. The fluid which it 
secretes is a glairy mucus, of a whitish colour, which being poured forth 
around the tip of the tongue covers it with a glutinous substance well 
adapted for causing the adhesion of any small body to it. 
The Ivory-billed Woodpecker, then, having discovered an insect or larva 
in a chink of the bark, is enabled by suddenly protruding its tongue, covered 
with thick mucus, and having a strong slender sharp point furnished with 
small reversed prickles, to seize it and draw it into the mouth. These 
prickles are of special use in drawing from its retreat in the wood those 
Vol. IV. 31 
