80 
ACTINOPTERYGII. 
P. 1748. Fragment of right side of head showing parts of P ri 
maxilla, maxilla, and dentary, with teeth ; also reman 
of a laminar inner hone of the mouth (probably cn 
pterygoid) covered with a cluster of minute stout conica 
teeth. The premaxillary teeth are the largest. 
Egerton Coll- 
43021. Right premaxilla, with remains of a cheek-plate w hic 
ornamented with radiating lines of fine tubercles- 
premaxilla (PI. I. figs. 4, 4 a) is shown to have be^ 
attached to the ethmoidal region throughout its *'° 
half, which is not much deepened ; and there is a ^ 
longitudinal groove for the overlap of the maxilla on i ■ 
hinder portion. The bone hears ten closely arrange i 
antero-posteriorly compressed teeth, two represented on ^ 
by the base of attachment, and all the others except 
foremost having lost the enamelled crown. . 
Purchased, l* 71- 
28424. Anterior end of small left dentary showing robu® 
mandibular symphysis. Mantell 0 
P. 641. Hinder half of small skull with opercular apparatus, P u,t ^ 
pyritised and imperfectly preserved, probably referab e ^ 
a young individual of this species. The specimen ^ 
marked by Egerton as intended to be the type of 
species Pomaphraetus egertoni, Agassiz, loc. cit. 
Egerton 
39699. Remains of equally small head, showing jaws. 
Purchased, 1 
INCERT.® SEDIS 
(? OSTEOGLOSSIDiE or ALBULID^®)- 
Genus PLETHODUS, Dixon. 
[Geol. Sussex, 1850, p. 366.] 
An imperfectly known genus, with deep laterally comp 1 
skull and small mouth. External bones not ornamented. r 
maxilla apparently fused with the short rostrum, this, the roaX \ g 
and dentary bearing minute teeth ; ectopterygoid very slender, a ^ 
nitb minute teeth; a large smooth concave plate, consisting 
vertical tubules of dentine fixed apparently to the parasphen 
