470 BRITISH FOSSIL REPTILES. 



differences of greater degree or value than may be set down to individual modifications. The 

 part defective and partly obscured by intrusive bones from other parts of the skeleton is un- 

 fortunately that which leaves the precise determination of structure unsatisfactory in the pre- 

 viously described specimen. A trace only of tympanic remains at 28, and of the descending 

 styloid process of the mastoid at 8 : the thick metacaqial of the wing-finger (iv, ?«)) intrudes 

 into the orbit, and overlaps the upper end of the malar (26). More of the part of the frontal 

 forming the superorbital arch (ii) is shown than in PI. 15. Part of the concave surface 

 of the orbital cavity beneath the superciliary ridge is here seen. The lacrymal (23) or 

 descending branch of the prefrontal (i4) meets the ascending process from the combined 

 malar and maxillary, dividing the orbital from the antoi'bital cavity. The true size and 

 shape of the latter vacuity (") is here well displayed. The maxillary styloid process (21") 

 rises, at the same angle backward as in PI. 15, to join the nasal (15). The medial branch 

 or ray of the premaxillary (22'), the end of which is depressed below the prefrontal in 

 PI. 15, preserves its position in the present specimen, and yields the true arched contour 

 of the profile of this remarkable skull. 



The entire vertical extent of the vast narial vacuity, n, is here given, the longitudinal 

 one, 3J inches, precisely agreeing with that in the first-described skull. The anterior 

 part of the premaxillary (22) shows, also, the same proportions and shape, viewed side- 

 ways, as in the first specimen. 



The conformity is instructively continued in the characters of the dental system. 

 The apex of the crown of the laniary (PL 10, 1) from the fore end of the premaxillary 

 shows the same curvature and proportions as in PI. 15; the same interval divides 

 it from the second laniary (2) ; the longer interval, again, occurs between the second 

 and the third laniary, with a longer and less ciu'ved crown. After an interval 

 of seven lines comes the fourth tooth (4), corresponding in size and shape with the one 

 which is displaced in PI. 15, 4'. After an interval of nine lines the apex of the crown of, 

 seemingly, the successor of the fifth laniary (5) appears. It may be, normally, smaller 

 than the rest; the socket of this tooth is feebly indicated in the subject of PL 15. The 

 sixth laniary (e) shows the same size and relative position as in that subject, and the same 

 may be said of the five succeeding teeth, save that the last is rather larger than in Pi. 15, 

 which also shows an additional small hind cuspidate tooth. The suture between the 

 premaxillary (22") and the maxillary (21) is more plainly discernible in the present 

 specimen. 



The extent of alveolar surface of the left upper jaw occupied by the above- described 

 dental series is 5 inches 3 lines. 



In the left ramus of the mandible two of the large anterior laniaries are in place ; one, 

 answering to the second in PL 15, 2', projects across the diastema between the second 

 and third tooth above ; in size, shape, and cm'vature, it resembles the second upper laniaiy, 

 close to which it terminates. The next mandibular tooth is larger, less curved, and crosses 

 the middle of the interval between the third and fourth upper laniaries. The tooth (I'j 



