6 
the posterior margin either of the opercular hones or the pectoral arch ; 
a hollow {orb.) seems to indicate the position of the orbit; the roof of 
the skull is tlattened, and the snout is sharply pointed. No teeth arc 
distinguishahle, and it seems likely that they were small. 
Axial Skeleton of Trunk . — The notochord, as usual, was persistent; 
and the cartilages of the neural and hannal arches and spines — as also the 
interspinons cartilages — were evidently only snperticially calcified, these being 
often represented in the fossils l)y a large core of calcitc surrounded by a 
thin film of skeletal matter, well shown in the figures. The neural arches 
and spines are short and stout ; and in the caudal region the hannal arclies 
and spines are similar. Long, slender, gently arched ribs arc well shown 
in the abdominal region, arranged in series as far as its termination almost 
immediately above the pelvic fins ; and in the type specimens there are about 
three pairs of these ribs in the space of 0‘02. 
Appemlicular Skeleton . — Of the paired fins, only one of the pelvics is 
preserved (IT. I, Pig. 2, plv .) ; and a few ro1)iist fin-rays exhibited by a 
fragmentary fossil (PI. II, Pig. 2) may pertain either to these fins or to the 
pectoral pair. Eacli pelvic fin is acutely lohate, its length being more than 
three times as great as its maximum l3rcadth ; and the long lobe is fringed 
in the usual manner with stiff tin-rays. The median fins form a continuous 
fringe round the hinder end of the body and are su])ported by a double scries 
of interspinous hones, tlie elements of the proximal scries being about twice 
the length of the distal. The interspinous hones appear to he even stouter 
than the neural and hcDinal spines to which they are apposed; and those of 
the proximal series, at least, have broadened ends. 
Squamation . — The tissues of the body have become converted into a 
black granular material, and the scales being very delicate, they are thus 
only recognizable with difficulty. The precise outlines of the scales cannot 
he distinguished in any specimen ; hut they arc evidently very small, and all 
arc marked by fine longitudinal striations. 
O?Y(Vr-GAN0IDEI. 
All the fishes of the Ilawkeshury-Wianamatta Series referal)lc to tlic 
hyostylic type, with true hones, fall under the denomination of Ganoidci, as 
defined and determined by Agassiz. In the prevailing uncertainty as to the 
correct limits and nomenclature of the great groups of fishes of this type, we 
