DEVELOPMENT OF THE SKULL IN THE MAMMALIA. 
105 
Here the nasals ( n .), narrowing steadily forwards, have their edge cut away from 
without, inwards, and not notched as in Manis. The upper part of the facial plate of 
the premaxillaries and maxillaries (px., rnx. ) can just be seen, and also the lacrymal; 
(see fig. 3, l.) under and outside the well-formed orbital rim, the jugal (j.) can be 
seen, and behind it the most projecting part of each squamosal ( sq .). 
The front two-thirds of the frontal suture, and the hinder third of the sagittal, 
are complete; behind the latter, the temporal fossa is evidently gaining somewhat 
upon the postero-external part of each parietal. The lambdoidal suture is in two 
limbs, as it were, in front, running forwards in the middle, and backwards, behind, 
between the two pa.rietals and the one large, wide, bracket-shaped intraparietal (i.p.); 
and behind, having a similar curve, and separating the intraparietal from the pro¬ 
jecting endoskeletal supraoccipital (s.o.). Outside the latter this plane is unossified, 
aud part of the projection is opisthotic, the swelling caused by the posterior canal 
being just caught by the eye. 
The side view (Plate 14, fig. 3) shows many things well, that are only partly visible 
in the other aspects. 
In front, the curious snout, with its alee, valve, and opening ( al.n ., n.v., e.n.), are 
shown, and these are followed by the oval face-plate of the premaxillary (px.) with 
its pedate lateral enlargement, below. The remaining three-fourths of the alveolar 
edge belongs to the maxillary (mx.), but the foremost third is edentulous. Surmounted 
by the long nasal (n.) this bone forms most of the side of the large, long face ; its 
upper margin ascends, at first gently, and then suddenly, its lower edge descends 
gently and sinuously back to the jugal (j.). The highest part contributes to the bony 
investment of the swelling ethmoidal mass ( al.e .) which it fails to cover, not meet¬ 
ing the frontal (f.) at that part. 
The hinder half of that preorbital tract is, however, covered by bone, but not by 
either of these ; the lacrymal (l.) comes in here as an antorbital wedge. It is a pyriform 
bone about the size of the face-plate of the premaxillary, has a straightish edge above, 
against the frontal, but dips into the maxillary below. The large canal is behind 
this rounded lobe ; then the bone flattens inwards to form a small orbital plate, and 
thickens, below, where it places a solid foot upon the fore part of the jugal. 
The hind part of the maxillary, the direction of which is forwards and upwards, is 
scooped for the broad overlapping fore end of the jugal (j.), so that the zygomatic 
part of the maxillary is almost half its hind border; this is burrowed by the upper 
maxillary nerve, which comes out at a moderate distance from the jugal, at the infra¬ 
orbital foramen (V 2 .). Thence, forwards, the face-plate of the maxillary is grooved 
twice—under the great swelling, and just above the alveolar margin ; a vascular 
foramen is seen in front of the great nerve passage, in this lower groove. 
development of the teeth. Rhynocoyon and Orycteropus come very near each other in this character; the 
former, indeed, lies, in this respect, between the Shrews and Moles on the one hand, and the almost 
Lemurine Tupaia on the other. 
MDCCCLXXXV. P 
