322 
ACTINOPTERYGII. 
P. 3693. A vertically crushed fish, probably of this species, ex¬ 
hibiting the small teeth in the maxilla; Lyme Regis. 
Enniskillen Coll. 
Ptycholepis monilifer, sp. nov. 
[Plate X. figs. 2-4.] 
Type. Portions of fish ; British Museum, 
The largest known species, probably attaining a length of not less 
than 0*6. The ridged ornament of the head fine and closely 
arranged, vermiculating, the ridges often interrupted and in part 
passing into tubercles. The stouter fin-rays ornamented with few 
oblique ridges of ganoine. Scales marked with numerous sharp, 
delicate ridges, sometimes branching, sometimes intercalated, the 
majority directed obliquely downwards and backwards and termi¬ 
nating in the serrations of the hinder border; the ridges in all the 
scales, except those of the caudal pedicle, passing forwards into a 
small sparsely tuberculated area at the anterior margin. 
Form. Sf Loc. Lower Lias : Dorsetshire. 
39868. Type specimen, comprising the right mandibular ramus, 
part of the branchiostegal apparatus, the dorsal and 
caudal fins, numerous scales, and other fragments ; Lyme 
Regis. The right mandibular ramus is shown of the 
natural size in PL X. fig. 2, but is imperfect posteriorly. 
A few small robust conical teeth in single series occur 
sparsely arranged at irregular intervals within the 
alveolar border, which exhibits a slightly sigmoidal 
curvature. The anterior extremity of the ramus is stout, 
though tapering to a blunt point; and this part is much 
more coarsely ridged than the remainder of the external 
surface. The superficial ridges are very irregular, 
frequently interrupted, branching, or intercalated, having 
a generally backward and downward direction ; and for 
a considerable space bordering the alveolar margin they 
are replaced by fine tubercles. Part of the course of a 
sensory canal is conspicuous postero-inferiorly; and a 
branch seems to extend from this upwards and forwards 
to the anterior extremity of the bone. The remains of 
the opercular bones are very fragmentary, but one highly- 
ornamented plate is evidently the suboperculum, and this 
is accidentally overlain by the large gular, which is quite 
smooth except in a small mesial tuberculated area ; but 
several of the long and narrow branchiostegal ra^s are 
