OF THE SKULL IN THE AMPHIBIA UEODELA. 201 



Below (PI. XXI. fig. 2, px) there is no appreciable palatine belt behind the tooth- 

 bearing edge right and left, and the outer parts of the bone are fiat (figs. 1, 3); but in the 

 middle this bone is greatly developed vertically. Below (fig. 2) the two crura appear in 

 front of the vomers ; but between those bones they have coalesced ; thus an oval space is 

 enclosed (m.n.p). The coalesced part runs some distance backwards as a "median 

 palatine process ; " behind it is another space, over which lies the internasal plate of 

 cartilage. 



Above (fig. 1, n.px) the original distinctness of the nasal processes is seen in front by a 

 deep hole, and behind by a sharp notch ; the two bars have grown into a very large 

 tract, which reaches back as far as the hind margin of the nasal sacs. 



The middle nasal passage (m.n.p) is made into a deep well, with an everted funnel- 

 like mouth, which is so greatly lipped behind as to overshadow the solid continuation of 

 the bone, and give it the appearance of being a totally distinct plate. The nasals, also, 

 clinging to the well's mouth, hide the median part ; and it, in turn, becoming narrow 

 and splintery, is imbricated on the frontals (/), wedging them apart. The large nasals 

 (fig. 1, n) are roughly pentagonal ; they have a concave edge forwards, towards the 

 nostrils (e.n), and a sigmoid edge outside ; they project towards one another behind the 

 notched lip of the nasal well, getting under it. Behind, they run transversely, with irre- 

 gular teeth, imbricating the frontals on the outer part, but not reaching nearly so far 

 back as the premaxillary. 



The ectethmoids (e.eth) are large conchoidal bones, that reach as far as the outer angle 

 of each nasal in front, and clamp the orbital edge of each frontal for some distance. 



Each maxillary (fig. 3, mx) is like a hatchet, the blade being its facial plate, and the 

 handle its zygomatic process ; but the blade is cut away in front ; in that notch there is 

 a graniform septo-maxillary (s.mx). 



To cover much of this long skull the frontals (/) are long ; they are widest in front, 

 are deflected over the cranial wall (fig. 3), but have little orbital development. Where 

 they begin to overlap the parietals (p) the skull is narrowest, and suggests the appearance 

 of the outline of an hour-glass. 



The end of the frontals is more than halfway from the foramen opticum (2) to the 

 foramen ovale (5) ; the frontal suture is most irregular ; the edges of the bones being 

 very thin, and, as it were, lacerated. 



The parietals (p) are much more elegantly finished. Each bone forms a wall-plate in 

 the interorbital region almost to the ectethmoid, and this part really becomes & paries, 

 as it descends with considerable steepness. The two bones gradually widen up to the 

 auditory masses, and then they suddenly attain their greatest width, not lessening much 

 behind, but ending transversely. Where they lie over the hind skull the parietals seem 

 to have been fitted on in a plastic condition, so thoroughly do they fit to each rising and 

 falling of the substance beneath. The dovetailing of the sagittal suture is perfectly 

 mammalian in its complexity ; the squamous sutures also, laterally, are very irregular 

 over the anterior canal (a.sc) ; the posterior canal (p.sc), where it joins the anterior, lifts 

 the lambdoidal edge of each parietal bone. The squamosals (sq) seem to grip the ear- 

 masses ; below, indeed, they are merely a thick wedge, binding the quadrate ; but above, 



