52 THE SKELETON OF THE FROG. 
upper jaw, are firmly connected with the cranium by 
anterior and posterior bony struts. 
a, The maxillary arch. 
a. Cartilage bones of maxillary arch. 
i. The pterygoid: a large triradiate bone, the inner 
limb of which is connected with the auditory 
capsule ; while the posterior limb runs back to 
the angle of the mouth, and the anterior limb 
forwards along the upper jaw to the palatine 
bone. 
ii. The palatine: a slender transverse bone connecting 
the upper jaw with the anterior end of the 
sphenethmoid. 
iii. The quadratojugal: a short bone forming the 
posterior part of the margin of the upper jaw. 
3. Membrane bones of maxillary arch. 
i: The maxilla: a long thin bone forming the greater 
part of the margin of the upper jaw: it bears 
teeth along its whole length which are anchylosed 
with the bone. It is connected behind with the 
quadratojugal ; about the middle of its length 
with the anterior limb of the pterygoid and with 
the palatine ; and in front with the premaxilla. 
ii, The premaxilla: a small bone which meets its 
fellow in the middle line in front, and so com- 
pletes the margin of the upper jaw: like the 
maxilla it bears teeth. It gives off on its dorsal 
surface a backwardly projecting process which 
forms part of the inner boundary of the nostril. 
b. The mandibular arch: the upper part of the arch 
remains unossified as the quadrate cartilage, which 
forms the suspensorium, 2.¢., serves to connect the 
lower jaw with the skull. It is a rod of cartilage 
which is fused above with the auditory capsule, and 
runs downwards and backwards to the angle of the 
mouth, where it is connected with the hinder end of 
