130 WEALDEN AND PURBECK FOSSIL FISHES. 



(socc.) occupies the middle third, and bears a vertical median crest on its hinder 

 hollowed face. The epiotic (epo.) is very prominent on each side, triangular in 

 shape when viewed from above, nearly as long as broad, and united in a finely- 

 toothed suture with the next otic element in front. Its upper face, like that of 

 the supraoccipital, is smooth, and must have been overlapped by the supratemporal. 

 Each parietal (pa.) is slightly more than twice as long as broad, meeting its fellow 

 in an almost straight median suture, and deeply interdigitating with the frontal 

 anteriorly. The middle of its hinder half is raised into a coarsely rugose boss, in 

 which the partly reticulating ridges tend to radiate from the transverse groove of 

 the slime-canal. Its anterior half is nearly smooth. Each squamosal (sq.) is about 

 as wide as the pair of parietals, and equally long. It unites in a slightly wavy 

 suture with the corresponding parietal, and in small digitations with the frontal, 

 while its outer border is somewhat concave. Its outer face is nearly smooth, with 

 some irregular pitting and longitudinal grooving. The relatively large frontals 

 (Jr.), which also meet in a nearly straight median suture, are much narrowed 

 between the relatively large orbits, and resemble the squamosals in the irregular 

 grooving and pitting of the nearly smooth outer face. The postfrontals or sphen- 

 otics (ptf.) form a conspicuous pair of smooth, truncated prominences about as long 

 as wide. There is a well-marked median depression in the cranial roof, beginning 

 behind between the parietal bosses, and widening and deepening to the greatest 

 extent between the hinder part of the orbits. The whole appearance of the bones 

 suggests a considerable development of the slime-apparatus. The otic region and 

 the basioccipital are well ossified, and the parasphenoid is comparatively stout, 

 bearing an elongated patch of minute teeth where it underlies the hinder part 

 of the orbit (seen in B.M. no. 21974). In some specimens there are broken 

 traces of very thin cheek-plates. As shown in the type specimen, the mandibular 

 suspensorium is arched forwards, so that the articulation for the mandible is 

 beneath the middle of the orbit. The hyomandibular is a deep and much expanded 

 thin lamina, of bone, but is known only in a crushed specimen (B.M. no. P. 4535). 

 It is strengthened b} r a vertical ridge, from which a short ridge proceeds at 

 right-angles to an elongated articular process for the operculum. The triangular 

 quadrate is cleft behind to accommodate a rod-shaped symplectic, and articulates 

 above with a large triangular metapterygoid. The ectopterygoid (best seen in 

 PL XXIV, fig. 4, eept.) is an arched, thin lamina of bone tapering forwards, and 

 the entopterygoid seems to be still thinner. It is uncertain whether these elements 

 bore teeth. As shown in the type specimen, the premaxilla is more extended 

 backwards than usual in Amioids ; and, as seen in another specimen (B.M. no. 

 P. 4535), it bears a single series of small but stout, hollow, conical teeth. The 

 maxilla, of which the middle portion is broken away in the type specimen, is 

 relatively large and arched, with a flattened and nearly smooth outer face, and the 

 convex oral border bearing minute teeth. Its posterior half is overlapped by two 



