DEVELOPMENT OF THE SKULL IN THE URODELES. 195 
1. In the first place, the horny sheaths to the edentulous jaws (the submarginal 
bones only, above and below, bearing teeth) make this skull unique as that of a 
“ Urodele.” 
2. The peculiar form of the hind skull, throwing out falcate horns right and left. 
3. The reappearance of the ichthyic paired dermo-ethmoids, and the suppression of 
the true nasals, the nasal roofs being arrested. 
4, As acorrelate of these submesial bones, the external position of the nasal processes 
of the premaxillaries, which are thrust apart by these bony wedges. Here the small 
maxillaries, as in the Siluroid fishes, are both present; they are symmetrical. 
5. The preauditory spike coming up from the parachordal plate. 
6. The short, dilated, unossified suspensorium, and the dilatation of the lower end of 
the squamosal as moulded upon it. 
7. The confluence of an epihyal with the suspensorium, and the enlargement of the 
stapes by the addition of a flat stalk, possibly a confluent “ pharyngohyal.” 
8. The arrest of the vomero-palatine bones, their sigmoid form, their elegant sigmoid 
rows of long hooked teeth, and the entire suppression of the cartilaginous and bony 
pterygoids. 
9. The presence of a definite prenasal cartilage. 
10. Besides the horny sheath and suppressed dentary teeth, the height, size, and curve 
of the mandible, with its very large condyle to fit into the equally large scooped facet of 
the quadrate. 
11. The large size of the ceratohyals, and the absence of hypohyal segments. 
12. The basihyal dilatation of the first basal piece, which carries the large first 
branchial; and the flat trifurcate form of the second basal piece, the proximal end of 
which carries the second ceratobranchial, which in turn carries the third and fourth 
arrested branchial arches. 
These twelve characters show how important a type of skull this is, and how very 
isolated this kind of Urodele is in its own order; also it may be pointed out that if 
the larva of a type so far removed from Siren as Triton has some important characters 
in common with it, and which explain it better than any thing found in the other 
“ Proteidea,” the “lacune” in this group of Amphibians must be very large indeed. 
On the Skull of the native Species of Newts. 
a. Chondrocranium of Larva of Smooth Newt (Lissotriton punctatus), 3 ich long. 
In this early stage (Pl. XL. fig. 1) I have shown what parts were first hardened into 
hyaline cartilage; this may be compared with what has been already figured by 
Professor Huxley in Triton, and by myself in Stredon (Proc. Zool. Soc. 1874, pl. 3, and 
Phil. Trans. 1877, pl. 23). 
From this small skull we learn that the trabecule in their hinder and more solid 
VOL. X1.— Part vi. No. 4.—January, 1882. 2H 
