APATEODUS. 



39 



and still smaller recurved teeth in front. Large teeth much laterally compressed, 

 and marked with very fine vertical striations in the basal portion. 



Description of Specimens. — The small fragment of jaw in the Mantell Collection, 

 described by Agassiz under the name of Saurocephalus striatus, is probably part of 

 the ectopterygoid of this species, but is insufficient for exact determination. A 

 small head in the Capron Collection (PL XI, figs. 1, la, Ih) was therefore chosen 

 for the type specimen when the species was first defined. 



The long and narrow, acutely pointed cranium is shown in the type specimen, 

 and more imperfectly in a smaller specimen described in the British Museum 

 Catalogue (pt. iv, p. 262, pi, xiv, fig. 2). It is remarkable for the lack of a tuber- 

 cular ornament on the radiating ridges of the frontal and parietal bones. The 



Fig. 9. Apateodus striatus, A. S. Woodward ; diagram of jaws, left sido, outer aspect.— English Chalk. 

 d., dentary ; ecpt., ectopterygoid ; mx., fragment of maxilla (remainder unsatisfactorily 

 known) ; pi., palatine ; pmx., premaxilla. 



supraoccipital (PI. XI, fig. 1 h, socc.) enters extensively into the cranial roof, though 

 the overlapping frontals may perhaps be partly removed in the type specimen. 

 The parietal (pa.) is a small triangular bone completing the postero-lateral angle of 

 the flattened part of the cranial roof between the projecting otic regions. The 

 very large frontals (/r.) extend on each side into a considerable supraorbital flange, 

 and the few ridges on each of these bones radiate from a point just above and 

 within the middle of the flange. The frontal region in the type specimen is broken 

 across at the anterior border of the orbit, and the attenuated rostral region has not 

 been satisfactorily observed. The mesethmoid, however, must have been very 

 little exposed. The sclerotic (fig. 2, scl.) is well ossified. 



The mandibular suspensorium is vertical, so that the quadrate articulation is 



