48 



FOSSIL REPTILIA OF THE 



present specimen, conform to the pterosaurian characteristics of these vertebrae, as shown 

 in those of Pterodacfylus Sedgwiclcii, described and figured in the ' Monograph on the 

 Fossil ReptiHa of the Cretaceous Formations,' Supplement No. 1 (1859), pp. 7 — 10, 

 PI. II, figs. 7 — 18 ; and in those of Fterodactylus simus, ib. Supplement No. Ill (1861), 

 p. 7, PI. II, figs. 1 — 5. 



The skull preserved in tlie present specimen agrees in size vi'itli that in the slab pre- 

 viously received (PI. XVII), repeats the characteristics of the gexwx's, Dimorphodon,i\\\A shows no 

 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 metacarpal of the wing-finger (iv, m), 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. XVII. 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 (14) meets the ascending process from the combined 

 malar and maxillary, dividing the orbital from the antorbital cavity. The true size and 

 shape of the latter vacuity (0) is here well dis[)layed. The maxillary styloid process (21") 

 rises, at the same angle backward as in PI. XVII, 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. XA^II, preserves its position in the present specimen, and yields the true arched 

 contour of the profile of this remarkable skull. 



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

 one, 3^ 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 crowai of the laniary (PI. XVIII, 1) from the fore end 

 of the premaxillary shows the same curvature and proportions as in PI. XVII; 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 curved 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. XVII, 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 PI. XVII. The 

 sixth laniary (6) shows the same size and relative ])Osition 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. XVII, 

 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. 



