328 
ACTINOPTERYGII. 
teristic teeth are also scattered below the jaw. The right 
hypohyal occurs, both large and robust. The large gular 
plate is completely preserved, two-thirds as broad as long, 
obtusely rounded in front, truncated behind. There are 
no other recognizable elements worthy of note, and the 
amount of disturbance to which the fossil has been sub¬ 
jected is indicated by the fact, that the left suboperculum 
is displaced to the hinder part of the caudal region. The 
exposed portion of this plate is slightly more than twice 
as broad as deep, ornamented with a very fine and close 
tuberculation ; and there is a small ascending process at 
its antero-superior angle. Remains of the pelvic fins 
opposed to the dorsal appear to comprise some slender 
fulcra. The caudal fin is best preserved, exhibiting its 
bifurcation and the very close articulation of its stout 
rays ; fulcra are displayed on both lobes, those on the 
upper lobe being especially large and distinctly uniserial 
at the base. Scales occur sparsely in the region of the 
pelvic, dorsal, anal, and caudal fins, all exhibiting the 
characteristic tubercular ornamentation. On the few 
principal flank-scales which are preserved, the tubercles 
have a tendency to elongation and pass in the hinder half 
into conspicuous striae. The peg and socket for articula¬ 
tion are very large, as usual. The ventral scales are 
shown to have been narrowed, as also are those immedi¬ 
ately covering the base of the caudal fin-rays. 
Enniskillen Coll. 
P. 3649. Fragments of mandible, apparently of this species, labelled 
Eugnathus polyodon by Agassiz and noticed by Egerton, 
loc. cit. 1868, p. 500 ; Lyme Regis. Enniskillen Coll. 
P. 3648 a. Imperfect and abraded large cranium, doubtfully of this 
species ; Lyme Regis. Enniskillen Coll. 
P. 875. Roof of a similar but much smaller skull, with a pair of otic 
bones displaced behind; Lyme Regis. Egerton Coll. 
©steorachis granulatus (Egerton). 
1868. Isocolum granulatum, Sir P. Egerton, Quart. Journ. Geol. Soc. 
vol. xxiv. p. 501. 
1872. Isocolum granulatum , Sir P. Egerton, Figs. & Descript. Brit, 
Organic Remains, dec. xiii. (Mem. Geol. Surv.), no. 4, pi. iv. 
Type. Trunk wanting head and tail; British Museum. 
A fish known only by a single specimen about half as large as 
