ETTGNATHIDiE. 
323 
exhibited, and distinctly marked with the finely ridged, 
partly tuberculated ornament. A few slender rays 
gradually increasing in length occur in front of the 
dorsal fin, but there are no fulcra; the stouter rays are 
much ornamented, as shown in the enlarged figure, Pl. X. 
fig. 4. The caudal fin is large and much forked, with 
stout rays anteriorly but very delicate rays behind; the 
superior fulcra are well developed, much elongated, and 
ornamented with short transverse rugae of ganoine; and 
the upper caudal lobe was evidently somewhat produced 
as usual in the genus, though the specimen is crushed 
and difficult of precise interpretation. Three scales from 
the region of the dorsal fin are shown enlarged in PI. X. 
fig. 3, and the lowermost exhibits the feeble rudiment of 
a peg-and-socket articulation. Purchased , 1866. 
Ptycholepis minor, Egerton. 
1852. Ptycholepis minor, Sir P. Egerton, Figs. & Descript. Brit. Or¬ 
ganic Remains, dec. vi. (Mem. Geol. Surv.), no. 7, pl. vii. 
Type. Imperfect fish ; British Museum. 
A small elongated species, the length of the head with opercular 
apparatus somewhat exceeding the maximum depth of the trunk 
and occupying about one-quarter of the total length of the fish. 
The ornament of the external bones consisting of comparatively 
delicate, well-spaced ridges ; the scales with few longitudinal 
furrows, sometimes partly convergent behind, and with some con¬ 
spicuous vertical folds at the anterior border. 
The feeble nature of the external ornament seems to be charac¬ 
teristic of this species, but it may be partly a deceptive appearance 
due to the state of fossilization. 
Form. Sf Log. Lower Lias : Leicestershire. 
P. 574, P. 3694. Type specimen, about 0*095 in length, in counter¬ 
part ; Barrow-on-Soar. Egerton § Enniskillen Colls. 
P. 862. Part of the head, abdominal region, and pectoral fin of a 
much larger fish ; Barrow-on-Soar. Egerton Coll. 
Ptycholepis avus, Kner. 
1866. Ptycholepis avus , R. Kuer, Sitzungsb. k. Akad. Wiss., math.- 
naturw. Cl. vol. liii. pt. i. p. 167, pl. ii. fig. 2. 
Type. Distorted fish ; Geological Survey Museum, Vienna. 
A very small species, attaining a length of about 0*09. Length of 
the head with opercular apparatus somewhat exceeding the maximum 
t 2 
