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Show 1 7 4 DR. A. SMITH WOODWARD ON [J u n e 7, (fig. 4). Tlie grooves for the slime-canals must also have been deep and conspicuous, as shown by the same fragment. The most interesting feature in the skull, its quadrate bone (figs. 1-3, qu.), is well preserved on the left side and exposed from behind. This bone is long and narrow, antero-posteriorly compressed, and inclined somewhat backwards. Its inner face is sheathed by a great vertical plate of the pterygoid, while its outer or lateral border is in complete contact with the bones of the cheek. It is quite clear that there was no postero-temporal cleft or vacuity; and the quadrate bears no impression of the external auditory meatus. There are no vacuities in the bony covering of the postorbital region of the cheek, and the limits of some of its constituent elements are well shown by the natural internal mould. The long and narrow ovoid squamosal (figs. 1, 2, sq.) is distinct; while the outline of the equally elongated and still narrower postorbital (pto.) can be traced without difficulty. There can also be little doubt that the postfrontal (ptf.) and prefrontal (prf.) exclude the parietals and frontals from the margin of the orbit. The parietofrontal region, however, cannot be satisfactorily interpreted. It seems probable that the parietals (pa.), which must have been relatively large, taper rapidly in front, where they extend nearly to the anterior border of the orbit. They must also have been either depressed or thickened in the median portion, where their anterior end articulates with the very narrow pair of frontals (fr .)-suggesting an arrangement nearly like that represented by Cope in the skidl of Cricotus *. The prosquanrosal (psq.) is an irregularly triangular plate, somewhat longer than deep, with the apex forwards. The quadrato-jugal (qj.) is nearly twice as long as its maximum depth. The jugal (j.) is especially elongated and forms the greater part of the infero-external border of the orbit (orb.), which is oval in shape and directed both laterally and upwards. There are also some traces of the edge of the postfrontal (ptf.), prefrontal (prf.), and lachrymal (la.) bones, but the middle part of the rostrum is lost. An internal mould of nearly the terminal portion of the snout (figs. 6, 7) demonstrates the slenderness of this region and the elongated shape of the *asal bones (na.). The palate is of the typically Labyrinthodont pattern, with a complete parasphenoid (fig. 6, pas.), which is laterally compressed in its middle portion. The large posterior lamina of the pterygoid, in a vertical plane, abutting on the quadrate, has already been mentioned. In front of this expansion the pterygoid of each side curves outwards to meet the jugal (and probably also the hinder end of the maxilla) in a long suture. Its extent anteriorly is uncertain owing to the absence of the middle of the rostrum. Further forwards the palatines (fig. 6, pi.) are rather * E. D. Cope, I'roc. Amer. Phil. Soc. vol. xvii. (1878), p. 529. |