PHOLIDOPHORUS. 103 



The abdominal region must have been rather stout, not much laterally compressed, 

 for it is often exposed from below (PL XXI, fig. 4) or distorted by crushing m 

 the fossils. Its ventral face must have been nearly flat. 



The postorbital part of the cranial roof is somewhat wider than long, and the 

 frontal region between the orbits is also comparatively wide. Except the narrow 

 overlapped margin at its straight occipital border, the roof is closely ornamented 

 with a very fine and inconspicuous rugosity ; the short parietals and squamosals 

 are crossed by a groove for the transverse slime-canal, and the frontals are pitted 

 along the outer margin by the openings of the longitudinal slime-canal (B. M. no. 

 28446). A large elongate-oval nasal bone, also ornamented, occurs in front of the 

 frontal (B. M. no. P. 10011). There is much ossification in the otic region; and 

 the parasphenoid bone is stout, bearing an elongated cluster of minute teeth 

 between and just in front of its lateral processes (B. M. no. 28445). 



The large orbit is surrounded by a ring of thin, smooth cheek-plates, traversed 



Fig. 34. — Pholidophorus ornatus, Agassiz; restoration, about half nat. size. — Middle Purbeck Beds; Swana° - e. 

 The cheek-plates partly restored from Pholidophorus micronyx, Ag. 



by a very large slime-canal, from which a few long branchlets radiate on the 

 postorbitals and preorbitals. There is an ossified sclerotic ring. 



In the mandibular suspensorium the hyomandibular is much expanded, and the 

 small quadrate is cleft behind as if for clasping a symplectic. The entopterygoid 

 is a thin lamina of bone, and a cluster of minute teeth in B. M. no. 28446 may 

 have belonged to it. The maxilla (PI. XX, fig. 6 a, mx.) and premaxilla (pmx.) are 

 comparatively stout bones with a smooth or only faintly rugose outer face. The 

 maxilla is a narrow band of bone curved upwards at its hinder end, where it is 

 deepest, and not much contracted at its anterior end, where it bears a slender 

 upwardly-directed process for attachment to the inner face of the premaxilla and 

 doubtless also to the palatine (especially well seen in Mus. Pract. Geo!, no. 28438). 

 Its oral border is nearly straight, bearing a single close regular series of small and 

 blunt styliform teeth ; its upper border, throughout the greater part of its length, 

 is overlapped by two thin and nearly smooth supramaxillary plates (smx.), the 



