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Fic. 45. Eurypholis boissiert Pictet. Restoration of the skull in lateral view. 
dentary is the largest of the three bones and forms the complete upper border, the 
majority of the lower border and the anterior two-thirds of the lateral face. The 
posterior edge of the dentary is V-shaped. Internally the dentary gives rise to a 
tooth bearing flange on the oral margin which supports a single series of evenly 
spaced teeth, about 10 in number. The teeth are pointed, laterally compressed, 
slightly recurved, hollow and with expanded bases. The teeth are of approximately 
the same size except for the penultimate tooth at the symphysial end of the mandible. 
This tooth is about twice the length of the other teeth in the row, but in all other 
respects closely resembles them. A second row of teeth on the oral margin of the 
mandible is composed of between 40 and 50 small, pointed, laterally compressed teeth 
which decrease in size backwards. In the posterior region these small teeth merge 
imperceptibly with the tubercular ornamentation on the lateral face of the mandible. 
The articular facet is hidden from external view by a vertical upgrowth of bone 
from the lateral face of the articular. The articular forms, laterally, the posterior 
third of the mandible, occluding the V-shaped indentation of the dentary. 
The angular is a small slip of bone forming the postero-ventral angle of the mand- 
ible beneath the articular facet. Its posterior face is slightly concave. 
The mandibular sensory canal traversed both the articular and the dentary 
ventro-laterally. The lateral face of the mandible is ornamented with numerous 
tubercles, which are more prominent at the symphysis where they are raised on to 
ridges. The tubercles radiate in lines back from the symphysis on the dentary, and 
on the articular upwards and forwards from below the articular facet. 
Opercular bones. The opercular bones are shown in lateral view in Text-figure 45. 
The preoperculum is deep and narrow and curved slightly forwards. It terminates 
