OF THE SKULL LN THE AMPHIBIA TJEODELA. 205 



the maxillary (mx). These latter bones unite freely with both the nasals and frontals ; 

 in Spelerpes they reach neither of these. The zygomatic process is also much more 

 developed, almost equal to what is seen in the Batrachians. 



On the right side (PL XXI. fig. 6, s.mx) there is a very small septomaxillary ; it rests 

 upon the junction of the maxillary with the premaxillary. Thus there are two instances 

 of asymmetry in this skull ; for on the left side the small stapedial rod is, contrary to 

 wont, distinct. 



The frontals and parietals (f,p) are exquisitely finished and smooth; yet there is but 

 little orbital development of either (fig. 8). Their sutures, the frontal and sagittal, seem 

 to belong to some much larger animal. They are like what we see in Mammals ; but the 

 dovetailing projection and notches are out of all proportion to the size of the bones thus 

 interlocked. 



The lambdoidal suture is squamous and almost transverse. 



The squamosal (sq) is more ichthyic than in the last ; it appears but little on the upper 

 surface (fig. 6), and rather serves above as a buttress to the ear-mass set under the 

 " tegnien." It is a short wedge, thick above and roughly pointed below. 



The parasphenoid (figs. 7, 8, pa.s) is more primordial in form than in Spelerpes ; it is 

 oblong in the long interorbital region, has a short triangular ascending basitemporal 

 process, and under the medulla oblongata it is almost straight-sided again, but wide ; it 

 ends subtransversely, with a bevelled crenate margin, a moderate distance in front of the 

 foramen magnum. 



The mandible (figs. 8, 9) is very stout and solid, and shows why the suspensorial 

 condyles should have been so well scooped. The dentary (d) reaches nearly to the end of 

 the ramus : it has a very high and thick edge at the chin for its fellow ; it has coalesced 

 with the splenial (fig. 9, sp), and has overlapped and partly absorbed the articulare (ar) 

 and the Meckelian rod. The articulare has largely ossified the cartilage, leaving, how- 

 ever, a solid cylindroidai condyle ; it sends upwards a strong rounded coronoid process 

 in front of the condyle. 



The hyobranchial series is much like that of Spelerpes ; it is still slenderer, and equally 

 unossified. The ceratohyals (fig 10, c.hy) are quite Like those of the last ; but the 

 hypohyals (h.liy) are stouter, and are directed forwards and inwards, instead of the 

 contrary direction seen in Spelerpes. The first cerato-branchial (c.br 1 ) is lanceolate, 

 instead of being dilated ventrally. The first epibranchial (e.br 1 ) is still slenderer than in 

 the last ; it is not dilated to receive the next rod, which is merely applied to its inner 

 side. The first cerato-branchial lies against the basal piece, as in the last, and the 

 second articulates with its end ; but this second bar (c.br 2 ) is longer than in Spelerpes, 

 and instead of being bent forward is bent backwards. 



The bony remnant of the second basibranchial (b.br 2 ) is only half as large as in the 

 last. It has two projections at the middle. Unlike the last, it is altogether bony, having 

 no soft cartilage tipping its horns. 



SECOND SERIES. — ZOOLOGY, VOL. II. 28 



