264 
MR. W. K. PARKER ON THE STRUCTURE AND 
is left alone—at most with but one companion—the other species—and its proper 
Family must have suffered very largely from causes of extinction. This is one of the 
lightest and most highly polished of all skulls—quite Bird like in this respect, and in 
the thorough fusion of all its cranial elements. 
The impression that rises first is that it is a foliaceous skull (Plate 39, fig. 4), as 
unlike other more familiar skulls, as the Leaf Insect is unlike normal Ortkoptera. 
The temporal and nasal regions are about equal, the orbital one-third shorter; this 
opens into the temporal, behind. The general convexity of the upper surface is made 
gently sinuous by the special convexities of the various bony elements of which it is 
composed; these have just been described, and will enable anyone to understand the 
finished and fused adult skull, in which, instead of sutures there are fine, and often 
clear, depressed lines. There is a supraorbital fossa on each side, as in aquatic Birds, as 
though it had a pair of nasal glands; these end sharply behind, and lead to a supra¬ 
orbital foramen, which is further forward than in Pteropus and its allies. Over the 
small hemispheres, as in Marsupials, the frontal region is flat, in front, and then rises 
gently ; the whole brain cavity has its form revealed in this way by a definite con¬ 
vexity, the outworks being well marked off. The orbit has the posterior fifth 
incomplete, for the finely turned supraorbital ridge ends in a large uncinate leaf of 
bone, the postorbital process and the jugal has a clean edge, growing up towards the 
postorbital process of the frontal; the lachrymal projects inward in the preorbital 
region, and forms about a fifth of the actual ridge of the orbit; its canal is small. In 
front of the lachrymal and jugal there is the small, but double, infraorbital foramen. 
The ridges on this skull serve the purposes both of beauty and of use ; the hind edge 
of the postorbital process curves forwards and then, at its sides, over the swelling 
brain-cavity, becomes the supratemporal ridge, which converges towards its fellow, 
getting within a half of the front distance, as they meet on the top of the inter¬ 
parietal. There the temporal fossa rounds itself, and is enclosed by the transverse 
occipital edge (Plate 39, fig. 4). This large oval enclosure, half as long again as the 
orbital territory, has then below it a low oblique wall which is very strong behind, and 
runs down over the meatus externus ; and, with two rounded elevations, one small and 
the other large, the sharp boundary line passes into the hinder edge of the ascending- 
uncinate postorbital process of the jugal bone. This outer boundary—orbital and 
temporal—is greatly bowed outwards in this depressed skull, in sharp contrast with 
the same parts in the neat narrow skull of Pteropus. Along the middle of the 
extensive temporal fossa, for the wide origin of the huge temporal muscle, the 
convexity of the wall of the skull cavity is clearly seen. The side view of the 
temporal region in this skull shows nothing new to the student of the higher 
Mammalia, but the form and condition of the parts is both Marsupial and also unique. 
Only the narrow outer end of the large transverse glenoid cavity is seen in this 
aspect of the skull, but the large postglenoid process, the notch for the deep 
tympanic trough, and the part of the squamosal overlying the mastoid process are best 
