19 
allusion to its possession of certain features prohahly destined to slied new 
light upon the precise affinities of the genus. Pive specimens exhibit its 
jirincipal cliaracters : — 
(a) Type-specimen (PI. IV, Pig. 7). 
(/>) A more imperfect fish, partly distorted (PI. IV, P^ig. 8). 
(c) Another example, of similar size and proportions, in counter- 
part. 
(cl) A fish with the well-preserved tail shown, of twice the natural 
size (PI. IV, Pig. 9.) 
(e) An imperfect small specimen, 0'058 in length, in counterpart. 
General Form . — The general form and proportions of the fish are 
well shown in the type-specimen (PI. IV, Ihg. 7). The trunk is relatively 
short and stout, the head, wdth the opercular apparatus, occupying almost a 
quarter of the total length, and the gape of the mouth is very wdde. The 
dorsal fin is for the most part in advance of the anal ; the upper lohe of the 
tail is conspicuously produced, and the caudal fin powerful (PI. IV, Pig. 9). 
Head and Opercular Apparatus . — Little can he discerned of the 
structure of the head, hut in the type-specimen and No. h (PI. IV, Pigs. 7, 8), 
the forward position of the eye, and the obliquity of the mandibular suspen- 
sorium, are evident ; and both in the first and other specimens there seem to 
he traces of minute conical teeth upon the margins of the jaws. The 
impression of an antero-posteriorly elongated hone upon the cheek is distinct 
(PI. IV, Pig. 7, x), hut indeterminalde ; and the external surface of all the 
elements is probably ornamented with fine strim and tuherculations (No. e). 
The operculum (op.) and suhopcrculum (s. op.) are narrow ; and, unless 
appearances are decej)tive in the type, the former is much smaller than the 
latter. 
Appendicular Skeleton . — The clavicle and supraclaviclc are ^vell 
showm in the type-specimen, the external striated surface of the former being 
narrower than that of the latter ; and in the same fossil, immediately below 
the posterior portion of the mandible, an antero-posteriorly elongated 
triangular area is -worthy of note. This feature, wdth a sharply-pointed 
anterior extremity and longitudinal mesial elevation, and, possil)ly, super- 
ficial rugm, may W'ell he interpreted as an infraclavicular element, though 
further evidence must he aAvaited before the determination can he affirmed as 
a fact. 
lla 74—90 
P 
