ESPECIALLY MYCTOPHOIDS 123 
The epiotics are present on the occipital border of the skull-roof as smooth hemi- 
spherical protuberances providing an articulatory surface for the dorsal limb of the 
post-temporal. 
Infraorbital bones. Traces of a circumorbital series of bones can be seen. The 
bones which are visible bear an external ornamentation of bony tubercles. Beneath 
the orbit there is a long shallow bone probably representing the first infraorbital, and 
behind this there is a larger bone (2nd infraorbital) which is angled and slightly more 
expanded and which shows the tube which housed the sensory canal. 
Jaws and suspensorium. The hyomandibular is large with a greatly elongated 
head. Ventrally the hyomandibular curves forwards so that the mandibular 
articulation lies below the centre of the bone. The lateral face of the hyomand- 
ibular is covered to a large extent by the postero-dorsal region of the metapterygoid. 
The anterior region of the head is only present as an impression in the matrix so 
that description is rendered difficult. The ectopterygoid would seem to be greatly 
extended as is also the palatine. The ectopterygoid bears a longitudinal series of 
evenly spaced teeth, but the dentition of the palatine is difficult to determine. At 
the anterior end of the rostrum an impression of a palatine tooth is visible. It is large 
and extends downwards over the impression of the lower jaw. Whether further 
palatine teeth were present cannot be observed on the specimen. No corresponding 
enlarged tooth of the dentary at the symphysis is present. Within the orbit, below 
what appears to be parasphenoid, the endopterygoid forms a flattened lamina of 
bone. The parasphenoid in the orbital region is slightly expanded ventro-laterally. 
The dermal upper jaw is only present as an impression in the rock. The pre- 
maxilla appears to be elongated and large, extending posteriorly to the orbit and 
bearing a lateral ornamentation of bony tubercles. The maxilla enters the oral edge 
of the upper jaw below the orbit. The premaxilla is toothed marginally but the 
maxilla appears to be untoothed. 
The mandible is prominent, elongate, relatively shallow and with a constricted 
symphysis. The lateral face is covered with a dense ornamentation of raised 
bony tubercles. The suture between the dentary and the articular could not be 
observed in the specimen. A dorsal extension of the articular lateral to the articular 
facet extends upwards and hides the facet and the quadrate condyle in lateral view. 
The retroarticular process is insignificant, and the coronoid process is low. The 
mandibular dentiton was not observed in the specimen. 
The preoperculum is deep and narrow although there are anterior and posterior 
expansions ventrally. The anterior edge of the bone follows the anterior curvature 
of the hyomandibular and the quadrate, and abuts against the posterior edges 
of both of these bones. Postero-ventrally there is a slight backwardly projecting 
spine. The lateral face of the preoperculum is ornamented with a uniform covering 
of bony tubercles. The operculum is large and about as deep as long with a straight 
anterior edge. The facet for the articulation with the hyomandibular is mid- 
way down the anterior edge of the bone. The dorsal edge of the operculum is 
rounded and the margin is produced posteriorly into a short spine. Ventrally the 
