206 PEOP. W. K. PAEKEE ON THE STETJCTUEE AND 



B. The Endocranmm of the adult Newt. 

 The hinder and middle skull are thoroughly ossified ; the fore part or nasal region 



is soft. 



The two sides over the foramen magnum (fig. 4,/ m) are separated by a very narrow 

 tract of cartilage ; this part and the crescentic internasal band (i.n. c) are all that keep 

 the two sides conjoined. 



The reason of this is that the greater part of the second basicranial bands (para- 

 chordals) have been absorbed, and not only these later, but also much of the earlier 

 bands ; for the whole of the posterior or parachordal part of the trabecula {tr) has been 

 absorbed also. 



Hence there are now only two hones on each side, namely the occipito-auditory mass 

 and the sphenethmoid {sp.e), the latter running along the whole extent of the orbital 

 region, and only separated from the former by a small cartilaginous wedge (fig. 4, tr). 

 Thus the shallow sella turcica and the faint and almost aborted bony cephalostyle are 

 now to be seen on the upper surface of tlie parasphenoid, the superficial " succedaneum " 

 of the proper basis cranii. 



The foramen magnum (/. m) is very large and obliquely supero-posterior ; the arch 

 over it narrows so as to have a very small keystone part of cartilage ; at the base there 

 is a wide semicircular emargination for the " odontoid rudiment." 



The occipital condyles {oc. c) are obliquely inturned, subpedunculate, reniform, and 

 postero-inferior ; the arch itself is narrow, the posterior canal {p. s. c) running very near 

 to the foramen magnum. 



The three canals {a. s. c, p. s. c, p. s. c) are large and protuberant, the tegmen tympani 

 {t. ty) scarcely overhanging tlie horizontal canal. 



Cartilage is seen in two places besides the condyles ; but only one of these parts 

 belongs to the capsules ; this is the stapes {st), which is oval, thick, and almost 

 transversely placed. 



The third part of cartilage belongs, like the condylar part, to the basal plate ; this is 

 the basipterygoid facet (fig. 6, l.pg), to which the bulbous pedicle {pd) is articulated. 

 The facial nerve (vn) escapes on the inner side of this joint, the ninth and tenth (ix, x) 

 pass out behind the opisthotic edge of the fenestra ovalis [st, vh). The vestibule in front 

 of that opening forms a very elegant crescentic swelling, as much marked as the curved 

 risings on the upper face of the capsule. 



The trigeminal nei-ve (fig. 3, v) escapes at a part of the skull where cartilage still 

 lingers, dividing the prootic from the sphenethmoid; the optic nerve (ii) escapes 

 through a smallish passage in the hinder fourth of the latter bone. 



A small auteorbital tract of cartilage in the trabecular wall is seen close behind the 

 perforated prefrontal (sp.e, p.f) ; the orbitonasal passes through the perforation in 

 the prefrontal. The nasal roofs (fig. 4, Ha)are nearly as large as the auditory capsules; 

 they are broadly crescentic in form, being deeply notched outside. In this notch the 

 nostrils {e. n) lie ; they are wide apart, but not so wide apart as the inner openings 



