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PROF. W. K. PARKER ON &AGITHOGNATHOUS BIRDS. 347 
become cartilage; and then the quadrate can be distinguished as a separate nodule, and 
the mandible as a separate bar. At that time the maxillo-palatine process of the embry- 
onic mandible has a pith of tissue in it more granular than the rest, but no cartilage ; 
the chick now corresponds exactly to the MWenobranchus, save that the pedicle does not 
pass into the trabecula by continuous cartilage. 
The same process may be traced in the Chelonia; and in them the free apex of the 
suspensorium, which, as in the bird, turns forwards as well as inwards, underlying the 
second and third branches of the trigeminal nerve, is pointed and permanently cartila- 
ginous, even in the largest Sea-Turtles. That pointed soft end of the suspensorium is 
the orbital process of the quadrate bone; in the bird this free end is often broad and 
spatulate. Here I may remark that I once held the erroneous opinion that this part 
answered to the orbital process of the Tadpole’s suspensorium—a cartilaginous leaf, 
folded over the outside of the temporal muscle, and only an evanescent structure. 
The “otic process” is only one of two parts that join the ear-sac in the Amphibia 
(see Huxley on Menobranchus, pl. 30. fig. 1); for, besides the proper otic process which 
coalesces in most Amphibia with the antero-superior region of that organ, the pedicle 
gives off a facet below, which is well seen in the common Frog, gliding on the smooth. 
antero-inferior face of the prootic region. 
Now, in birds, the huge otic process of the suspensorium (the head of the quadrate) 
generally has an outer and an inner fork, and always, save in Ostriches and Tinamous, 
has two articular facets, even in the Gallinaceous birds and the Parrots, where the head 
is most undivided. 
This inner facet does not, however, correspond with the otic facet of the amphibian 
pedicle, but is a mere fork of the “ otic process.” 
So far we see that the suspensorium of the bird is altogether attached to the head 
(auditory region) by joints with joint-cavities, whilst in the Amphibia it is attached by 
bands and joints. 
It is not an easy matter to harmonize the other parts of the palato-mandibular appa- 
ratus. The ascending process of the Urodela is a mere fibrous band in the Batrachia 
proper; and I do not think that Prof. Owen’s view is tenable (see Huxley on Meno- 
branchus, note to p. 189), namely that it answers to the epipterygoid columella of the 
Lizard. In Lizards and, as I have also discovered, in the Chelonia there are two ptery- 
goid bones—one the broad flat membrane bone which forms so much’of the posterior 
palate (the true pterygoid), and the other a rod-like bone lying above the great plate ; 
this is the columella or epipterygoid. 
In the Chelonia, when recently hatched, this bone is seen to be the separate ossifica- 
tion of the only part of the pterygo-palatine arcade which acquires any thing like a 
cartilaginous consistency: it is the postero-superior extremity of the arcade; and its 
hinder ¢i/ted end articulates with the apex of the free pedicle, joining it at right angles, 
and altogether in front of it; it cannot, therefore, answer accurately to the Amphibian 
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