318 
ACTINOPTERYGII. 
Type. Imperfectly preserved fish; British Museum. 
The type species, attaining a length of about 0*35. Length of 
head with opercular apparatus equalling the maximum depth of the 
trunk and nearly one-quarter of the total length of the fish. The 
ridged ornament of the head coarse, very rarely mingled with few 
tubercles, and covering all the external bones except the gular 
plate and branchiostegal rays, which are nearly smooth; the supra- 
clavicle also ornamented with finer transverse ridges. Most of the 
ridges on the cranium, cheeks, aud opercular bones longitudinal; 
the ridges on the upper portion of the dentary and hinder half of 
maxilla oblique. The stouter fin-rays ornamented with few fine 
longitudinal ridges of ganoine ; pelvic fins arising midway between 
the pectorals and the caudal; dorsal fin with slightly more than 
20 rays, arising well in advance of the pelvic pair. Scales marked 
with from one to four or five delicate, irregular, longitudinal furrows, 
sometimes discontinuous, sometimes branching, rarely reaching the 
hinder border except on the middle of the abdominal flank, and 
producing an ornament of large, incomplete, rounded ridges ; the 
hinder border deeply and coarsely denticulated. 
Form. § Log. Upper Lias : Yorkshire, Wiirtemberg, and Yonne, 
Prance. 
P. 3688. A much crushed and distorted fish described and figured 
by Agassiz, op. cit. 1844, to be regarded as the type 
specimen ; Whitby, Yorkshire. One of the pelvic fins is 
mistaken in the original description for the anal; and the 
obscure caudal extremity, with traces of the caudal fin, is 
very inaccurately drawn. The appearance of teeth in the 
mandible is deceptive. Enniskillen Coll. 
P. 858-a. Two imperfect specimens displaying some of the head- 
bones and the greater part of the squamation; Whitby. 
The first specimen exhibits the gaping mouth, but no 
teeth ; and portions of all the fins except the anal are 
preserved. The second specimen is more imperfect, but 
shows remains of the smooth branchiostegals and gular 
plate. Egerton Coll. 
P. 3691. Remains of the hinder portion of the head and the 
imperfectly preserved trunk of a large fish, labelled by 
Agassiz ; Whitby. Enniskillen Coll. 
P. 5222. Imperfect head and ventral aspect of the abdominal region 
of a fish preserved in a nodule ; Whitby. The bases of a 
single regular series of small teeth are exhibited on the 
