264 PROF. OWEN ON THE ANATOMY 
of the os quadratum obliquely forwards to the lower and posterior margin of the external 
coronoid depression : a strong posterior ligament descends from the ex-occipital process 
to the posterior angle of the jaw. These strong ligaments are an essential part of the 
mechanism of a beak which is destined to be forcibly thrust into the ground, and used 
in a variety of ways, to overcome considerable resistance. 
The posterior expanded surface of the palate is quite smooth in the Apteryx, as in 
the larger Struthionide, in which the ridges and papille, commonly present in other 
birds, are altogether absent. 
The tongue’, as was conjectured by Mr. Yarrell, is short, much shorter indeed than the 
interspace of the united rami of the lower jaw ; it nevertheless presents a greater rela- 
tive development than in other Struthious birds. It presents a compressed, narrow, 
elongated, triangular form, with the apex truncate and slightly notched ; the lateral and 
posterior margins entire: it is 8 lines in length, 4 lines broad at the base, | line across the 
apex. The anterior half consists of a simple plate of a white, elastic, semitransparent, 
horny substance, gently concave above ; behind this part, the exterior covering, which is 
lost in, or blended with, the horny plate, gradually becomes distinct, and assumes the 
character of a mucous membrane, and is pitted with several very minute glandular fora- 
mina: this membrane is reflected over the posterior margin of the tongue, forming a 
crescentic fold, with the concavity towards the glottis ; but here, as well as on every 
other part of the tongue, it is devoid of spines or papille. This fold can be brought 
back by the retractors of the os hyoides, so as to cover the glottis ; in which movement the 
uro-hyal process plays in a cellular sheath beneath the Jarynz, and its office seems to be 
to give steadiness to the protractile and retractile movements of the tongue. The su- 
perficial and principal protractor of the tongue represents the genio-hyoideus, its two 
lateral halves being separated and removed from the symphysis to within an inch of the 
angle of the jaw, whence its fibres pass almost directly backwards, and converge, to be 
inserted into the extremity of the bony cornu of the os hyoides. The mylo-hyoideus arises 
from the inner side of the lower jaw, commencing posteriorly about an inch from the 
angle, and extending forwards to within the same distance of the symphysis ; the fibres 
become gradually fewer as they are placed more forwards ; they meet to be inserted at 
a middle tendinous line posteriorly, and are separated anteriorly by a tendon about a 
line in breadth : these tendons are attached to the body of the os hyoides, and retract it: 
a few tendinous threads connect also the posterior margin of the muscle with the ante- 
rior part of the upper larynz. On the removal of this muscle two deeper-seated pro- 
tractors of the tongue are brought into view ; they arise by a very thin aponeurosis from 
near the angle of the jaw, and pass directly backwards, to be inserted into the base of 
the cornua. These muscles adhere closely to the membrane, filling up the interspace of 
the rami of the lower jaw. The cartilaginous extremities of the cornua of the os hyoides 
curve upwards, and terminate about a line behind the angles of the jaw. 
) Pl, XLVIII. Figg. 1. & 2. 
