632 
MR. W. K. PARKER OK THE STRUCTURE AKJD 
It then ascends, leaning forwards, and melts into the top bar. The orbito-sphenoids 
(o.s.) clamp the hind part of trabecular crest (presphenoid), but are developed sepa¬ 
rately. The hind part, only, is developed in the Snake, and of the alisphenoid only 
the bar that finishes the “foramen ovale;” whilst the presphenoidal crest, passing into 
the ethmoidal, does not exist, and no crest appears until we reach the nasal capsules. 
Between the notched crest of the trabeculm and the arched orbito-sphenoids there is 
a large oval interorbital notch, not “ fenestra,” as in the Birds. 
The large orbito-sphenoids are notched in front, the lower narrow fork running fur¬ 
thest forwards. Where the septum rises highest below that fork, there the ethmoidal 
region begins; its end in front is marked off from the septum nasi by a fenestra (p.s., 
p.e., s.n., c.f.f.). 
From thence we have the rising and then descending septum nasi, which ends in 
front in a pah’ of short cornua trabeculae, confluent with the down-turned nasal roofs. 
These parts can be seen in an inner view of the dissected and divided skull (Plate 41, 
fig. 5); but the remainder of the skull, not yet described, is seen in the basal view 
(Plate 41, fig. 2). 
A rather broad band of bone now separates the two basal fontanelles ( py ., p.b.c.f.), 
but in front of the lesser space {py.) there is no bone; that opening, the pituitary 
space, is circular behind, and runs forwards to a point. This is caused by the con¬ 
vergence of the filiform, terete trabeculae, which at this part are like those of a Snake, 
and, as in the Snake, they are ossified where they diverge most, and then join, and 
become ankylosed. with the parasphenoicl ( jpa.s .). 
The ossified part ( b.s .) runs round the front of the posterior fenestra, upwards and 
forwards into the “ posterior clmoicl wall,” and outwards with a forward bend into the 
large padded “ basipterygoid processes” (h.pxj). Upon the diverging hind parts of 
the basisphenoid the prootics (figs. 3 and 5, prco.) rest, with the intervention, at present, 
of a synchondrosial tract. 
The trabecular base of the orbito-nasal septum continues rounded and thickish, up 
to the frontal wall (Plate 40, figs. 7, 8). 
The endoskeletal part of the mandibular arch is complex, and more highly specialized 
in the Lizard than in any other type known to me. I have, however, already given 
my views of its nature and meaning in the description of the skull of the adult; there 
remains now the task of showing what state these parts are in in the ripe young. 
The hooked and hollowed quadrate (Plate 41, figs. 1-3, q.) is still largely cartilaginous 
above and below ; the “ articulare ” (ar. ) leaves the condyle soft, and all Meckel’s 
cartilage ( Mk .) except the thick proximal end. 
The long pterygoid bone (pg.) reaches nearly to the corresponding vomer (v.) ; it 
quite reaches that bone ( normally ) in Hatteria, and in the embryos of most Birds. 
The epipterygoid {epg.) rests upon a facet of cartilage on the pterygoid, a shallow 
cup-and-ball joint existing there ; the rod itself is only ossified for two-thirds of its 
height (Plate 41, fig. 3, epg.), the top and bottom being cartilaginous. 
