390 
ACTIXOPTERYG1I. 
The following specimens are not specifically determined:— 
P. 3704. Imperfect head and abdominal region, the latter much 
deepened and with remarkably small scales; Upper Lias, 
Ilminster, Somersetshire. The operculum is triangular 
and slightly deeper than broad. Enniskillen Coll. 
P. 900. Imperfect head, pectoral fin, and anterior scales of a small 
fish ; Ilminster. Egerton Coll. 
32245. Remains of small fish with relatively small scales; Upper 
Lias, Curcy, Normandy. Tesson Coll. 
An imperfect head of Pachycormus from the Upper Lias of Lozere, 
Prance, has also been described under the name of Cephenoplosus 
typus by H. E. Sauvage, Revue Sci. Nat. vol. ii. (1874), p. 430, 
pi. viii. Nothing is known of the species from the Lower Lias of 
Lyme Regis named Pachycormus leptosteus by Agassiz, Poiss. Foss, 
vol. ii. pt. ii. (1844), p. 114. 
The fragmentary head and pectoral fin described as follows is 
commonly compared with Pachycormus :— 
Sciurichthys gigas — Lycodus gigas , F. A. Quenstedt, Der Jura 
(1858), p. 240, pi. xxxiii. fig. 1.—Upper Lias; Holzmaden, 
Wiirtemberg. [Tubingen University Museum.] 
Quenstedt places next to this some problematical cranial bones 
from the Upper Lias of Ohmden, described under the provisional 
name of Pachylepis , op. cit. p. 241, pi. xxxiii. figs. 12-15. 
Genus HYPSOCCRMUS, Wagner. 
[Gelehrte Anzeig. k. bay. Akad. Wiss. vol. 1. I860, p. 214.] 
Trunk laterally compressed and irregularly fusiform, relatively 
deep in the abdominal region, very narrow' at the extremity of the 
caudal pedicle. Head small and less deep than the trunk; rostrum 
moderately produced ; premaxilla large and triangular in shape; 
maxilla long and slender. Dentition powerful, all the principal 
teeth romfd or oval in section, wdthout sharp edges, and fixed in 
incomplete sockets; those of the vomerine and splenial bones 
especially large ; those of the maxilla, premaxilla, and dentary in 
a single widely-spaced series, with minute clustered teeth exter¬ 
nally ; those of the pterygoid bones more or less granular. Gular 
plate present. Ossifications in sheath of notochord absent; ribs 
short and slender. Fin-fulcra minute or absent. Pectoral fins large 
and sickle-shaped, with straight anterior border stiffened by the 
fusion of the foremost three or four rays, W'hich gradually increase 
