216 
ACTINOPTERTGII. 
inwards to the ethmoidal region, also slightly deepened 
again in its hinder third, where it bears the spaced series 
of comparatively large teeth. Its lower margin is 
ornamented with fine tubercles throughout its length* 
The supramaxilla, premaxilla, and dentary are also im¬ 
perfectly preserved; and part of the thickened ecto- 
pterygoid is exposed within. The lower end of the 
preoperculum bears the usual posterior spine, and its 
fine tubercular ornament extends in a narrow band at 
least halfway up the ascending limb of the bone. The 
operculum is ornamented with close radiating lines of fine 
tubercles; and the more delicately marked suboperculum 
is shown to be relatively small. The clavicle is partly 
ornamented with elongated tubercles in radiating series; 
and the supraclavicle exhibits longitudinal rows of 
tubercles in its exposed hinder half. Enniskillen Coll. 
P. 4537, -a. Pine small head with opercular apparatus, and a more 
imperfect specimen; Burham. Enniskillen Coll. 
35104, -05. Remains of a smaller head with vertebrae, also part of 
another small head in two pieces ; Rochester, Kent. In 
the first specimen the great extent of the premaxilla is 
well shown. Par chased ^ 1860. 
47298. Remains of an equally small head and abdominal region, 
with traces of the dorsal and paired fins; Lower Chalk, 
Dover. Judging from sections of the constricted vertebral 
centra, a persistent thread of notochord seems to have 
pierced them. Gardner Coll. 
P. 9252. Remains of large head, the mandible 0*09 in length; 
English Chalk. History unknown. 
47916. More fragmentary remains of large head ; Lov/er Chalk, 
Durham. Presented hy the Hon. Robert Marsham, 1877. 
41108. Pragmentary remains of small head ; Lower Chalk, Durham, 
Kent. Purchasedy 1868. 
49082. Pragmentary head showing the ornamented anterior ex¬ 
pansion of the premaxillae ; Durham. Mrs. Smith’s Coll. 
P. 9044. Remains of small head ; Blue Bell Hill, Durham. 
Presented hy S. J. Hawkins^ Esq., 1891. 
