DEVELOPMENT OP THE SKULL IN THE MAMMALIA. 
231 
The frontals and parietals (f, p.) have a nearly equal axial length, but the former 
are far inferior to the parietals in width. 
The frontal and coronal sutures are perfect, at present, and are semi-squamous ; the 
two frontals mutually overlapping each other, in this place and that, and the parietals 
overlapping the frontals laterally. 
Where the frontals are wedged in between the nasals and maxillaries there they are 
very thin, sharply angular in form, and splintered at their edges. 
Behind, they run in between the parietals, with strong dentations ; their orbital edge 
is rounded and smooth, and has a gently arcuate outline. The parietals (p.) run 
as far forwards, below, as they retreat, above; inside the gently concave temporal 
fossae, they swell together, into a dome-like structure, which is divided by the sagittal 
suture. This is larger than the general convexity of the frontals ; but it is enlarged 
still more by the subconcave part which extends into the temporal fossae. The 
squamous suture with the squamosal (sq.) is not well seen from above; the wedge¬ 
like fore part of the interparietal (i.p.) is more clearly defined than its narrow, 
extended outer wings ; it is rather a large bone, and is convex above, where it fits to 
the fore margin of the supraoccipital ( s.o .). It there forms the lambdoidal crest; but 
the sagittal crest has not any existence, at present, and there is a shallow concavity 
running across the skull where the parietals and interparietals meet, which connects 
together the two temporal fossae. 
The side view (Plate 34, fig. 3) brings out things that are not well seen from above; 
it shows a dorsal line gently sinuous, with even fewer interruptions than the lateral 
outline which is broken by the hind part of the maxillaries; compared with normal 
skulls it looks as though it had been artificially elongated whilst in a plastic state; 
the great distance of the teeth from each other increases this appearance. The 
dentary edge of the premaxillary ( px .) is only one-fifth the extent of that of the 
maxillary (mx.); the whole line is gently sinuous, convex in front and behind, 
and concave in the middle. The nasals ( n .) are scarcely seen from this aspect, but 
the maxillary is well displayed, with its upper facial plate, its infraorbital hollow 
passage and narrow bridge (V 3 .), and the hills and hollows caused by the series of 
teeth. The maxillary ends, behind, in thin lobes, the upper of these is broad, and 
overlaps the small angular lachrymal (l.) with its canal ( l.c .) in front, in the notch 
between the upper and lower outer lobes; the lower lobe is sharp and upturned, it is 
the end of the alveolar region. The third lobe is a flattish tridentate tract, further 
inwards, and binds upon the palatine (pa.). The orbital plate of the frontal (f) runs 
down to the middle tooth of this inner lobe of the maxillary ; its hollowest space is 
the shortish tract between the lachrymal and the overlapping parietal. The hinder and 
most convex part of the frontal where it passes under the parietal is not marked by 
any lines or grooves, but in front of that tract it is sinuous, rising and falling over the 
turbinal coils within, which shine through it, as through a thin plate of horn. The 
hinder margin of the orbital plate is notched, deeply, by the outstanding alisphenoid 
