62 
ACTIXOPTERYGII. 
shown. The ossification of the hyomandibular is especiall}' 
dense, as indicated by its upper end (Jim.) exposed on 
the right, and by its opercular process seen on the left 
side. The boundaries of the large, expanded metapterygoid 
(mpt.) are not completely shown; but its long antero¬ 
inferior border is exhibited in contact with the quadrate 
(qu.) on each side of the fossil. The latter element is 
very concave on its outer face immediately behind the 
articular condyle, and sends backwards a long process to 
clasp the symplectic, which is not clearly distinguishable, 
but seems to have been long and narrow. An excavation 
in the matrix on the left side has revealed a portion 
of bone bearing the characteristic PisocZiis-teeth (.r.), 
which may be entopterygoid. The maxilla (m.u.) is frag¬ 
mentary on both sides, and the premaxilla is destroyed; but 
the right mandibular ramus is well-displayed, showing the 
suture between the angular (ag.) and dentary (cl.) bones. 
The articular facette for the quadrate condyle is remarkably 
concave; the bases of a cluster of minute teeth are vaguel}’' 
indicated near the symphysis of the dentary. The sclerotic 
of the eye (sd.) is ossified, and there are traces of cheek- 
plates on the right side. The preoperculum (x:>.op.) is 
narrow and bent closely round the hinder border of the 
mandibular suspensorium. The operculum (op.) and sub¬ 
operculum (s.op>.) are much fractured on the right side, 
crushed inwards on the left; but it is evident that the 
former is not quite twice as deep as its maximum width, 
while the maximum depth of the latter equals somewhat 
more than half its width. The interoperculum is not 
definitely identifiable ; but the branchiostegal rays (hr.) 
are well preserved on the right side to the number of nine 
or ten, though probably others are lost or obscured in 
front. Traces apparently of the basibranchial and robust 
hyoid bones project from the matrix below. The pectoral 
arch and large scales are too imperfect for description. 
Three short and deep vertebrae are indicated in section. 
History unJcnoivn. 
39439. Imperfect cranium showing parasphenoiddentition, described 
and figured in Ann. Mag. Nat. Hist. [6] vol. xi. (1893), 
p. 357, pi. xvii.; Sheppey. Bowerhank Coll. 
30528. Fragmentary rostrum, shown of one half the natural size from 
the palatal aspect in PL IV. fig. 2; Sheppey. Abraded 
