OCR Text |
Show 1897.] FROM NORTH AUSTRALIA. 331 almost equalling the greatest combined breadth of the nasals. Naso-premaxillary suture not longer than the naso-maxillary suture. Nasal notch rather deep, nasals projecting about 5 mm. beyond their junction with the premaxillae. Interorbital region very deeply concave in the middle, its edges raised up into high, prominent, sharp-edged ridges, running parallel and not uniting behind. Meatus audltorlus externus swollen (as in P. peregrlnus) ; bullae not inflated. Anterior palatine foramina short, barely extending backwards to the level of p1. Posterior palate with two large foramina, extending from the anterior border of m2 to beyond TO4, and only separated from the border of choanae by a thread-thick bony bridge. TEETH. Teeth strong. The diastema between i3 and c is 2-3 mm.; length of molars 1-3 together about 13 mm. The typical dental formula is :- . 1.2.3 1.2.3 _ 1 1.0.3.4 1 • 2.3.4_ *• 1 .0.0 0 r 1.2.0 5 C" 0> P- 0.0.0.4 > m' 1 .2.3.4* Upper jaw.-Incisors : anterior incisors separated in front; i2 elongated horizontally, its antero-posterior diameter equalling twice that of I3. Distinct diastemata in front of and behind tbe canine. Canine present, small, half the size (or less) of I3; in one specimen it is absent on one side. Premolars. P1 present or absent, rudimentary, smaller than the canine ; in three of eleven skulls it is absent on one side1. P2 absent; in one of eleven skulls (the largest of all) it is present but perfectly rudimentary, its crown hardly being raised above the gum2. P3 and p4 always present; size of p3 about half that of p4, the latter about two-thirds the size of TO1. Molars large, typical; length of molar series reaching 17 mm. Lower jaw.-Incisors. I1 long, lancet-shaped, broadest in the middle (as in Ps. albertlsi); upper and lower edge with an angle separating the enamel-covered cutting portion from the root, which is narrower. I2 present or absent, always minute ; in eleven skulls it is present in five, absent in six. I3 always absent. Canine absent. Premolars. P1 absent or present; in four skulls of eleven it is present, minute3. 1 The dental formula in these three specimens is: on one side p. 0 0 0 4. on the other side (typical) ' „",.'. ., 1.2.3.4 2 In this specimen, a male, the formula is on both sides: p. 0 0<04. 1.0.3.4 3 Dental formula in these specimens : p. x 0 0 4. 22* |