OF THE SKULL IN THE AMPHIBIA UKODELA. 187 



of the premaxillary and of the corresponding' maxillary (px, mx). The "helve" of 

 the blade is the palatine, and each blade is wrought into sutural teeth to unite, by squa- 

 mous suture, with the underlying fore end of the palatine, which carries, now, all the 

 true teeth; for the vomer has become edentulous. 



We have thus, in this species, a most instructive analysis given us of the skull of the 

 two last kinds (compare PL XVII. fig. 6, PI. XVIII. fig. 2, and PL XIX. fig. 5). More- 

 over, this skull, which stands related to the last two, like a young individual, is also 

 intermediate between them on one hand and Desmognathm and Spelerpes on the other 

 (PL XXL). 



In AmUystoma (Phil. Trans. 1877, pi. 21. fig. 6) the palatine, as in Polypterus and 

 the Batrachia, is a transverse bone, which, with the ethmo-palatine, its cartilaginous 

 consort, represents the ornithic " os uncinatum." In Spelerpes and Desmognathm 

 (PL XXI.) I shall describe a palatine which is both transversely and basally developed, 

 as in those Batrachia which have a broad inner part (e. g. Bnfo agua). 



In Taricha (PL XIX. fig. 5) the palatine {pa) has no transverse part, but it is longi- 

 tudinal or basal, altogether ; yet it does not run much more than half as far backwards 

 as in the last two kinds. 



The median palatine region of the premaxillary (px) is a grooved emarginate wedge. 

 The nasal process (fig. 4) is a very curious structure ; there are two spatulate free pro- 

 cesses, but these are confluent from the middle forwards ; and this part is largely sulcate, 

 the valley being surrounded by a ridge, which is round in front, and which °at the sides 

 passes into the free lobes. 



The uniting portion ends in a rounded notch, which is converted into a large oval 

 hole by the internasal cartilage behind. The same cartilage is seen to bound it below 

 (fig. 5, m.n.p), between the hooked vomers. 



In this careful finish of a useless middle cavity or passage,. Taricha approaches 

 Spelerpes and Desmognathm (PL XXI.) ; those surroundings are not less perfect in the 

 last two kinds (Pis. XVII. & XVIII.). 



The maxillary (mx) in this flatter skull has a lower facial plate ; its palatine portion 

 also (fig. 5) is less extensive ; but its jugal process is unusually long, passing some 

 distance behind the pterygoid (pg). The septo-maxiUary is not apparent. 



The nasals (») are more rounded and thinner; the orbital process of the ectethmoid 

 (e.eth) is a sharper spur, but forms part of a very similar superorbital ridge ; that part 

 of the frontal (/) articulates over the temporal fossa with the squamosal (sq). 



The frontals do not quite cover the internasal cartilages, and on each side they are 

 dinted by the nasal processes of the premaxillary, and overlapped by the nasals and 

 ectethmouls. In their turn they are imbricated upon the parietals (p), which run on 

 between, as well as beneath them. 



Together the parietals (p) form a roughly pentagonal plate, divided irregularly by the 

 sagittal suture. 



Each bone is imbricated upon the prootic over the anterior canal (a.sc), and the two 

 run straight across the occipital arch, a little in front of the shelving upper ed<*e of the 

 foramen magnum. 



