194 
•ACTIXOPTITRYGII. 
as long as its maximum depth, ornamented with conspicuous 
tubercles, of which the large majority are not placed on ridges ; 
more than six enlarged mandibular teeth. Teeth much compressed, 
sometimes with very dhlicate striations but not serrated. 
Form. ^ Log. Turonian (?) : Kent and Sussex. 
P. 1703. The tj^pe specimen, shown of the natural size in PL XI. 
fig. 2 ; Chalk, Kent. Only part of the left lateral border 
of the cranium is shown above the orbit and otic region, 
and exhibits the usual ornament of tubercles on ridges. 
A fragment of the parasphenoid, the left hyomandibular 
(Jim.'), and left metapterygoid, are exposed, but too 
imperfect for description. The fractured remains of the 
left premaxilla with its characteristic ornament, 
obscure the pain tine and part of the ectopterygoid {ecpt.)^ 
but most of the teeth of these inner elements are shown. 
The palatine tooth {pal.) is much the largest and exhibits 
very feeble traces of longitudinal striation. The left 
mandibular ramus is well-displayed, though imperfect 
anteriorly and a little fractured behind. The upper part 
of the dentary {d.) is flattened on the outer face and 
ornamented by tubercles with no definite arrangement, 
while in its lower portion a few tuberculated ridges 
radiate from the symphysis backwards and downwards; 
The precise boundary of the articulo-angular {ag.), which 
'is similarly ornamented, is not clear. The mandibular 
teeth are straight and more slender than those of the 
palato-pterygoid arcade. The deep and narrow tuber- 
'culated preoperculum (p.op.) is partly shown, and there 
are traces of a small reflection at its lower end which may 
have been a short spine. The operculum (op.), exhibiting 
'numerous radiating lines of small tubercles, is for the 
most part beautifully preserved ; and the equally ornate 
suboperculum (s.oj?.), with rows of tubercles chiefly 
directed downwards, is also represented by a large 
fragment. Egerton Coll. 
P. 5416. Kemains of another head in a small block of chalk, the 
left palato-pterygoid arcade figured in Proc. Geol. Assoc, 
vol. X. pi. i. fig. 6 ; Chalk, Lewes. The imperfect right 
premaxilla exhibits the characteristic ornamentation much 
abraded, bears very slender well-spaced teeth, and is 
shown of the natural size in PI. XI. fig. 3. The right 
palato-pterygoid arcade is exposed from the inner aspect, 
