172 PEOF. W. K. PAEKEE ON THE MOEPHOLOGY 



Many other bony plates, however, have been developed in the overlying fibrous tracts ; 

 the chief of these is the parasphenoid (pa.s). This bone rounds gently to a blunt point 

 behind, beneath the foramen magnum, and to two blunt points in front, close behind 

 the prenasal rostrum ; the basitemporal region is widest and is notched. Running in an 

 arched manner round the front of the parasphenoid is a chain of four dentigerous bones ; 

 the foremost of these are the larger, these are the vomers («) ; they keep their width 

 throughout. Behind the vomers are the palatines (pa) ; these are little wedges, with 

 their point behind. In the last stage they were continuous with a pterygoid expansion ; 

 this is now a large distinct bone. 



This pterygoid bone (pg) is a large broad wedge, whose point, severed from the pointed 

 end of the palatine, looks forward, but lies further outwards than the end of the palatine. 

 Its hinder end is roughly semicircular, and forms a clamp to the suspensorium from the 

 exit of the trigeminal nerve inwards to the quadrate condyle outwards. The outer 

 surface of the suspensorium is bouDd by its own splint, the squamosal (sq), which also 

 helps to make the tegmen tympani outside the horizontal canal. 



The great upper fontanelle is closed in by two pairs of bones, the frontals and parietals 

 (f, p), that are nearly equal ; the parietal is a much larger bone in the Urodeles than 

 in the Anura. 



The parietals not only run in and form a wall-plate to the trabecular crest, but they 

 also overlie the hind part of the frontals ; these, again, are in their turn overlapped by 

 the nasals and nasal processes of the premaxillaries. The nasals (fig. 5, n) are small 

 subcrescentic bones ; they cover in but little of the nasal roof. The nasal processes of 

 the premaxillaries [n,px) are as long as, but narrower than, the marginal part of these 

 bones : they are larger in the Urodeles than in the Anura. External to these the 

 maxillaries (mx) have enlarged ; they have an ascending facial part, and a styloid 

 zygomatic process (fig. 5) ; but the palatal part, as in the premaxillaries, is very narrow. 

 On their upper edge, below the external nostril (e.n), there is a small septo-maxillary 

 (s.m.v). 



Between the hind part of each maxillary and nasal, on the hinder part of the nasal 

 dome, there is a thin bony lamina, answering to the ectosteal plate of the Fishes' pre- 

 frontal (ectethmoid) ; it retains its distinctness here, and thus has to be called the 

 external ectethmoid (e.eth). The sphenethmoidal bony centres are all that are yet 

 wanting to make up the sum of the bony centres seen in the skull of the adult. 



The metamorphosis of the inferior arches takes place after birth ; they have now 

 merely increased in size ; the branchials are now at their fullest development, and will 

 soon suffer extensive absorption. 



3rd Stage. — Skull of the adult Salamandra maculosa. 



The skull of the adult of this species shows at once the likeness and the unlikeness of 

 this type to that of an average Batrachian ; yet in reality this skull differs as much 

 from that of Rana temporaria or of Btifo vulgaris as it did in its early conditions and in 

 the mode of its metamorphosis. But scattered up and down the great Batrachian 

 " Order " there are remarkably generalized types, whose skulls, now in this and now in 



