DEVELOPMENT OF THE SKULL IN THE MAMMALIA. 
63 
frontals begin wider than the nasals at the suture, and then are cut away gently in 
an arcuate manner over the orbits. This crescentic rim is rounded, and beyond it 
there is, towards the frontal suture, a gentle crescentic hollowing of the surface. The 
postorbital process is rounded and short, and the last third of the bone behind it 
widens up to the parietal. Longer than the nasal suture, the frontal and saggital 
sutures are nearly equal, and the wide swelling parietals (p.) gently dip towards the 
temporal and supraoccipital regions. In the latter place, from above, the endoskeletal 
keystone of the back skull ( s.o .), is just seen as a transversely spindle-shaped tract. 
Laterally, the squamosals (sq.) can just be seen flanking the parietals. 
In front the alinasal porches ( al.n .) can be seen, more than from below ; and, in the 
distance, the top of the dentary region of the premaxillaries (px.) comes into view. 
But behind, and outside these parts, the maxillaries and nasals (mx., n.) meet with no 
premaxillary process intervening ; thus there is a deep triangular notch right and 
left. Outside that notch is the swelling first tooth-socket, then a deep rounded 
indentation, and then a hinder swelling of the maxillary, where it binds upon the 
small burrowmd lacrymal ( l ., l.c.) ; these strong round knuckles of the maxillaries give 
the skull a remarkable form. Behind these parts, in the distance, the jugals (j.) show 
their scooped upper or suborbital face, with their thickened outer edge. 
The side view (Plate 10, fig. 3) shows many parts with their relations not well seen 
in the other aspects. The circular narial cartilage and hole (al.n., e.n.) is seen in front of 
the recess caused by the suppression of the facial process of the premaxillary (px.), which 
is just seen, below. The nasals are seen, now, to be, not one-fourth shorter than the 
frontals (fig. 2, n.,f ), but only one-seventh ; the outer and hinder lobe of the bone, 
also, shows well, wedging in between the frontal and maxillary, over the lacrymal (/.) 
of which we have got, here, the best view. It is not so small as the other aspects 
suggest, but has a good oblong facial tract, thus forming a thick perforated rim to the 
orbit, and it runs inwards as a small antorbital plate. Then, the maxillary (mx.) 
below, also, takes a good piece from the fore edge of the scooped orbital plate of the 
frontal by running up inside the fore rim, and joining the small antorbital plate of 
the lacrymal. This tract appears to me to be a very unusual antorbital growth of 
the maxillary, preventing any appearance of the lateral ethmoid as a “ pars plana.” 
The outer part of the maxillary is a large high plate, worked well in to the lateral notch 
of the nasal, and carrying on its scooped descending hind edge the lacrymal and jugal. 
Its last tooth-socket and tooth can be seen, here, inside the notched jugal; three more 
teeth are seen, in their convex sockets, and then a gap before we come to the swelling 
socket of the large tusk. About two-thirds of the orbit is rimmed with bone, and 
the lower half of the rim is formed by the free-ended notched jugal (j.). Over its 
margin is seen the orbital plate of the frontal, under the short thick supraorbital eave ; 
it is notched twice, below, and the ophthalmic nerve (V 1 .) takes its remarkable course 
under the front notch, below which some unossified orbitosphenoid (o..s.) is still to 
be seen. Under and in the other notch that plate is ossified, and deep in, under the 
