DEVELOPMENT OF THE SKULL IN THE BATRACHIA. 
263 
palatine is always a distinct cartilage and rather late in appearance ; the pterygoid 
cartilage is in the Urodele an outgrowth from the suspensorium—a little later in 
appearing; the post-palatine is a separate cartilage, also. 
The hinge for the jaw is in them, at first, just where it gets to be in the trans¬ 
forming Tadpole, when the tail is nearly absorbed ; the ceratodiyal has in that stage 
the same position it has, at first, in the embryo of the Urodele. There are no labials, 
no extra-branchials, and no spiracular cartilage in the Urodeles,* and they develop 
three or four true intra- branchial arches. 
The floor is never finished with cartilage any more than the roof; the former is 
often divided into two compartments by the persistence, for a long period, of the 
apices of the trabeculae, which keep separate from the posterior parachordal tracts. 
In one species (viz.: Ranodon sibiricus ; see Wiedersheim, “ Das Kopfskelet der 
Urodelen,” plate 5, figs. 69, 70), the palato-quadrate arch becomes continuous; an 
exception similar to that of Bufo vulgaris, where it becomes segmented. 
The frontals and parietals are always long narrow bones ; the paraspheuoid is a 
broad generalised plate ; the vomers and palatines are both dentigerous ; the latter 
become strangely transposed, during metamorphosis, in the “ Caducibranchiata.” 
The quadrate ossifies of itself, and there is neither a quadrato-jugal nor a jugal; the 
bony arch of the cheek is always (as in the Anura Aglossa and Teleostei) unfinished. 
The squamosal has no postorbital process, but it lias, at times, a very distinct lower 
supratemporal process. The premaxillaries are generally double ; and sometimes there 
is only one. The maxillaries are large in the higher, but small, or even suppressed, 
in the lower, types. 
Besides the cerato-hyal, and its lower hypo-hyal segment or segments, united by 
a distinct basi-hyal, there is in the larger and some of the smaller kinds, an epi-hyal 
element, not infrequently subdivided, so as to show a “ pharyngo-hyal ” also. This 
last is found in the “ suspensorio-stapedial ” ligament, and the former in the “ liyo- 
suspensorialthe upper piece answers to the pharyngo-hyal of the Chimcera, and to 
the inter-stapedial of the Frog; the lower piece to the epi-hyal of the one, and to 
the medio-stapedial of the other.f 
Even this very imperfect comparison of the skull of the Urodeles, with what we 
have just seen in the Anura, shows how far these groups are apart, notwithstanding 
their many points of similarity ; a thorough comparison of the larval skull of the latter, 
with that of the Lamprey, will be given in my next communication, which will treat 
of the cranio-facial skeleton of that Fish. 
* In my paper on. the Urodeles (Phil. Trans., 1877, p. 587) I expressed an opinion, now found to be 
wrong, viz.: that the cartilage which in some Urodeles passes from the suspensorium to the stapes was 
the same as the “ spiracular cartilage ” of the Tadpole. 
f In Bana halecina and B. palustris (Plate 5, figs. 5 and 10) I have shown the Acipenserine 
subdivision of the Prog’s columella; of course the “inter-stapedial” is due to the normal subdivision of 
the proximal piece. 
