Page:The Osteology of the Reptiles.pdf/36

18 and maxillae, above with postorbitals, and, by an extensive overlapping suture, with the squamosals and quadrate jugals; on the inner side perhaps with the ectopterygoids.

Absent in some Ophidia (Fig. 59 ) and some lizards (Fig. 56). In the lizards (Fig. 55) they may not articulate with the squamosals.

Intertemporals (it). An amphibian bone known only in Seymouria (Figs. 2, 19) of the Cotylosauria, intercalated between the postfrontal, parietal, supratemporal, and postorbital.

Supratemporals (st). Primitively (Figs. 2, 4, 19) articulating at the sides of the parietals with the postfrontal and postorbital anteriorly, the tabulars behind, and the squamosals on the outer side; interrupted by the otic notch in Seymouria (Figs. 2, 19).

Absent in the more specialized Cotylosauria, probably all Theromorpha, and all other reptiles save possibly the Ichthyosauria (p. 62) and Squamata (p. 65). Generally known as the posterior bone of the arch in the Squamata (Fig. 55, ta). [But see tabular below.]

Tabulars (t). Primitively (Figs. 2, 4, 22) on the dorsal surface of the skull in the Cotylosauria, as in the Amphibia, at the outer side of the interparietals, articulating with the squamosals and supratemporals, with the upper end of the quadrates and the outer end of the paroccipitals, whence the name "paroccipital plates" given to them by Baur. They are known to be absent in but a single genus of Cotylosauria; are probably present in most Theromorpha (Figs. 33, 42 ) and Therapsida (Fig. 44 ), and some "Pseudosuchia" (Fig. 65 ). The tabular has been identified by the author as the posterior bone of the arch in the Squamata (p. 62), and Ichthyosauria (p. 62), usually and perhaps correctly called the supratemporal. It is unknown in other reptiles.

Squamosals (sq). Primitively (Figs. 2, 4) articulating with tabulars and supratemporals above, in the absence of the latter directly with the parietals (Figs. 33, 53 ). Below, they cover the posterior part of the temporal region, extending back of the quadrate to articulate with the pterygoids (Fig. 7), overlapping extensively the quadratojugals on the sides (Fig. 33 ), and articulating in front with jugals and postorbitals.

In later reptiles the squamosal has undergone many changes, but is always present, though sometimes vestigial in the Chelonia,