OF THE SKULL IN THE AMPHIBIA URODELA. 177 



chin to the coronoid process. The Salamander has no inento-Meckelian hone, and the 

 Frog has no splenial. The angle of the jaw is attached to the outside of the apes of the 

 ceratohyal hy the mandibulo-hyoid ligament {c.hy, m.h.l). The same part of the hyoid 

 is attached to the suspeusorium by the hyosuspeusorial ligament. 



The suspensorium is attached to the oval cartilaginous stapes by the suspensorio- 

 stapedial ligament. The first cleft closes early. Thus there is no tympano-eustachian 

 cavity, no " annulus," and therefore no membrana tympani. The columella is re- 

 presented by the suspensorio-stapedial ligament, over which the facial nerve passes. 



Thus the high type of Urodele is much less specialized in these respects than the Frog. 

 It is a much higher creature than the Frog's Tadpole prior to the absorption of the tail, 

 for in its own diverging line it ascends to a considerable vertebrate height ; yet in some 

 metamorphic peculiarities it rises no higher than the Batrachian larva. 



The hyobranchial series of arches have undergone great change (PL XIV. figs. 3 & 7), 

 and have all continued soft except the distal part of the 2nd basibranchial (b.br). 



The hyoid bar {c.hy) has become much flattened, and its ventral end is the wider ; the 

 distal piece is quite detached, and is now directed forwards instead of backwards, parallel 

 with the 1st ceratobranchial (c.br 1 ), which is a longer rod and is more directly 

 attached to the ceratohyal. 



The 1st epibranchial (e.br 1 ) has reached the median piece, some distance behind its 

 distal segment. It is still a large cartilage, but is made still larger by the confluence 

 with it of the 2nd epibranchial, which is now fused with its own ceratobranchial piece 

 (fig. 3, c.br). These latter bars, right and left, articulate with the oblique end of 

 the 1st basibranchial (b.br 1 ), which now has four cartilages directly articulated to it 

 instead of two (figs. 3 & 7). All except the broad end of the 2nd basibranchial (b.br) 

 has been absorbed, and that has become a F"-shaped bone, with the tips of its crura soft. 

 It is now a median bilobate " thyrohyal," being applied to the front of the larynx — 

 a very simple structure, but cartilaginous. 



This is, on the whole, the kind and degree of modification undergone by this series of 

 cartilages in the " Caducibranchs ;" but we shall find some curious modifications in 

 other types of the group. 



Species 2. — Nbtojahthalmus viridescens. 



1st Stage. — Larva? 1 inch 2§ lines long *. 



My large larvae of this North- American Newt show some very instructive conditions of 

 the urodelous skull ; the skull of the adult also is very important. The larvae at this 

 stage are as much developed, on the whole, as the ripe young of the Spotted Salamander 

 (PI. XV.) ; I suspect them to have been nearly ready for metamorphosis into Caduci- 

 branchs. They show a remarkable difference as to the time at which certain changes 

 take place. In some respects they are far less developed than my first stage of the type 

 just described (PI. XIV.), and in others are far more advanced than the second. The 



* This and the remainder of the types to be described in the present paper are the gift of Prof. St. George 

 llivart, F.P.S. 



