ESPECIALLY MYCTOPHOIDS 135 
slender, lying beneath the maxilla. The complete oral edge of the premaxilla has a 
fringe of minute conical teeth. 
The maxilla is also long and thin and along most of its length is closely associated 
with the premaxilla. The anterior part of the maxilla curves inwards and this 
medial region is associated with a very small maxillary process on the dorsal surface 
of the palatine. Anteriorly the maxilla also articulates with the vomer and the 
mesethmoid. The maxilla enters the gape posterior to the premaxilla, and supports 
a row of teeth. These teeth are enlarged, well spaced and inclined forwards. 
The maxilla supports a single supramaxilla which is elongate and pointed 
anteriorly. The lateral face of the supramaxilla is ornamented with radiating 
tuberculated ridges. 
Mandible. The mandible is shown in medial and lateral views in Text-figures 60 
and 61. The dentary forms the greater part of both dorsal and ventral edges of 
the mandible, and is constricted at the symphysis. The oral margin of the dentary 
is produced into a medial tooth bearing flange. The teeth are arranged in two rows, 
a marginal row of smaller teeth and an inner row of larger ones. These teeth are 
identical in form to those on the palato-pterygoid. 
The articular forms the posterior part of the dorsal border of the mandible as well 
as part of the ventral border and lateral face. The articular facet is concave and 
transversely orientated. The articular extends anteriorly on to the medial face of 
the dentary. The mandibular sensory canal ran within a tube in the ventro-lateral 
region of both the articular and dentary. The lateral face of the mandible is smooth 
dorsally, but ventrally is ornamented with small tubercles. The angular is a small 
knob of bone attached to the postero-ventral region of the articular. 
Opercular bones. The opercular bones are shown in medial and lateral views in 
Text-figures 60 and 61. The preoperculum is long and narrow with a slight forward 
curvature ventrally. The upper limit of the bone lies behind the hyomandibular 
head whilst the anterior edge rests against the rear edges of both the hyomandibular 
and the quadrate. The preopercular sensory canal ran in a groove on the lateral 
face of the bone. The flange overhanging the groove is ornamented with ridges and 
tubercles. This ornamentation continues on the lower end of the bone. 
The operculum has an irregularly concave ventral edge. From the articular 
facet an internal horizontal strengthening ridge crosses the operculum to terminate on 
the posterior edge. The lateral face of the operculum is ornamented with minute 
tubercles radiating outwards from the region of the opercular facet. The sub- 
operculum is large and deep with its dorsal edge covered by the ventral part of the 
operculum. Ventrally the suboperculum is thin and membranous and has an 
ornamentation of bony tubercles. The interoperculum lies medial to the ventral 
part of the preoperculum, and has a similar ornamentation to the other opercular 
bones. 
Pectoral girdle and fin. The pectoral girdle is shown in medial view in Text- 
figure 62. The post-temporal has a large, plate-like upper limb articulating with the 
epiotic, and a shorter strut-like ventral limb articulating with the intercalar. The 
supracleithrum articulated with the posterior region of the post-temporal, and the 
