184 PEOF. W. K. PARKER ON THE MORPHOLOGY 



form belongs to the same natural group as the last ; and the morphological differences 

 between the two are, indeed, interesting, but somewhat trivial. 



The occipito-otic region (PL XVIII. figs. 1, 2) is strongly in contrast with the rest of 

 the skull ; the w r hole skull is a sort of short stout mallet, the handle being all the middle 

 and front regions, and the head the ear-masses, formed into one by the occipital arch 

 and its over- and underlying splints. 



The arch of the occiput leans forwards, so as to show the floor from above. This floor 

 is widely emarginate, to receive the odontoid vertebra (not process), which is an exact 

 miniature of the odontoid process of the Ox. The exoccipital bones are very closely 

 applied both above and below ; the wavy facets (oc.c) are subpedunculate and look down- 

 wards and inwards. Above, the huge canals of the ear (a.sc, p.sc) elbow inwards to the 

 rim of the arch ; they leave a hollow outside, which swells again with the horizontal 

 canal (h.sc) ; this is overlapped by the squamosal (sq). The anterior region of the 

 auditory sacs and occipital arch is covered by the parietals (p) ; below (fig. 2), the pedicle 

 of the suspensorium, invested by the pterygoid, hides the ear-mass in front. 



The vestibule, behind the foramen for the 7th nerve, is w r cll defined, but does not 

 bulge so much as in the last kind (PI. XVII.). The fenestra ovalis, in its hinder margin, 

 looks outwards and backwards. The oval stapes (st), with its nucleus of bone in the 

 centre, resembles, on a large scale, the blood-corpuscle of a Newt. 



The tegmen is irregularly scooped, and is enlarged by the squamosal (fig. 2, sq). The 

 whole mass is very wide, directly transverse behind, Avith the middle region having the 

 condyles projecting on each side of the median emargination. The pterygoids, suspen- 

 sorio , and squamosals, together, grow like trifurcate antlers, from the broad, transversely 

 oblong, occipito-otic mass. 



From the auditory capsules, onwards, the skull-walls are ossified, as " sphenethmoids," 

 nearly up to the internal nostril (fig. 2, i) ; the rest remains soft (figs. 2 & 3, sp.e). The 

 external nostril is well rimmed by the olfactory cartilage (na, e.n). The internal nostril 

 is margined behind by the ethmo-palatine cartilage ie.pa), which coalesces with the 

 nasal wall. 



The optic nerve (2) passes out at the hinder third of the sphenethmoid ; the 5th (5) 

 betw r een that bone and the prootic {pro, sp.e), and the orbitonasal pierces the ecteth- 

 moidal plate (e.eth, 5). 



When the skull is seen from its fore end (fig. 6) the large fenestra for the olfactory 

 crura (1) are seen ; the 9th and 10th nerves (fig. 2. 9, 10) emerge close on the outside 

 of the occipital condyles (oc.c) ; the first of these burrows in the capsule, but the 

 vagus escapes in the chink between it and the exoccipital, so that a small bar of bone 

 can generally be seen dividing the foramen into two. 



As in the last species, the suspensorium looks forwards as well as outwards, not gain- 

 ing that backward position seen in the Salamander (PL XVI.) ; it is well ossified (q), and 

 has a cylindroidal condyle. The otic process {ot.p) is triangular, soft, and free. 



The pterygoid cartilage {e.pg) has been ossified by the pterygoid bone, especially at its 

 origin, and thus a separate epipterygoid has been formed. The strong pterygoid bone 



