THE SKELETON 29 



portions of the maxillae. The posterior edge of the pre-frontal is free 

 and forms a bony rim to the antero-dorsal border of the orbit. The 

 ductus naso-lacrimalis (d.nas-lc.) enters a foramen at the postero- 

 lateral angle of the bone, and passes antero-lateralwards under it and 

 the pars facialis of the maxilla to enter the nasal capsule near the 

 external narial opening. 



W. K. Parker (1882) describes and figures a septo-maxillary at 

 the antero-lateral angle of the apertura nasalis externa, between the 

 maxilla and the pre-maxilla, but he is the only author to do so. 

 Stadtmuller (1924) declares himself totally unable to find it in any 

 of his sections, and Lapage (1928) also failed to detect any such bone. 

 Bruner (1902) describes the bone in certain other Urodeles but says 

 it is wanting in Salamandra. The present investigation confirms the 

 result of the later workers. It therefore seems that Parker must have 

 been mistaken or that he encountered a very abnormal specimen. In 

 view of Lapage's work the latter alternative is unlikely. 



The brain-case proper is roofed over by two pairs of investing 

 bones, namely the frontals and parietals; they remain separate 

 throughout life and do not fuse as in the Frog. 



ThQ frontals (o.fr.) are large and extend far forwards under the 

 prenasal processes of the pre-maxillae, while their antero-lateral bor- 

 ders also underlie the nasals for some distance and meet the mesial 

 edges of the pre-frontals. The lateral edge of each frontal turns down 

 ventrallyand meets the orbito-sphenoid, while posteriorly the frontals 

 overlap the anterior edges of the parietals. The sagittal suture is very 

 irregular and is by no means a straight line. There is no post-orbital 

 process as in some Urodeles. 



^ht parietals (o.par.) lie immediately posterior to the frontals and 

 have approximately the same superficial area. They complete the 

 roof of the cranial cavity, while their posterior ends spread out later- 

 ally over the mesial portions of the ear capsules. N. trochlearis may 

 penetrate the parietal, but, in older animals at least, this nerve usually 

 passes through a foramen in the orbito-sphenoid. The parietals do 

 not extend quite to the dorsal rim of the foramen magnum but leave 

 a portion of the tectum synotkum exposed. The dorsal surface of the 

 frontals and parietals is very flat, or even slightly concave as seen in 

 transverse section, and while both are relatively thick bones they are 

 very transparent, so that it is quite easy to distinguish the main 

 features of the brain through them, even in the adult. 



The squamosals (o.sq.) (jympanicum^ Wiedersheim ; paraquadrate^ 

 Gaupp) are paired splint-like bones lying on the dorsal side 

 of the quadrates, to which they become very closely fixed. Each 



