350 RAMSAY H. TRAQUAIR ON THE 
meets with. It occurs also in the west of Scotland, as in the Possil ironstones. 
No specimens, save those from Belgium mentioned above, have as yet been 
found in any other country, nor has it in any case occurred above the horizon 
of the Millstone grit. 
Structure—In Eurynotus (Plate IIT. fig. 1) the body is rather deeply fusiform, 
the tail very heterocercal, deeply cleft and inequilobate. There are largely 
developed pectorals and abdominally placed ventrals; the anal is acuminate 
with a short base, like that of most Paleoniscidz. But the dorsal fin is very 
long, extending from opposite the origin of the ventrals as far as the tail 
pedicle ; in front it is high and acuminate, but posteriorly it becomes low and 
fringe-like. 
The structure of the fins is, however, altogether Palzoniscoid. The rays 
are closely set, their demi-rays strongly imbricating from before backwards, 
except in the hinder part of the fins, especially in the fringe-like portion of the 
dorsal and the upper lobe of the caudal, where little imbrication is observable. 
They are ganoid externally, and articulated throughout ; the joints simulating 
the appearance of small scales. The stronger rays of the anterior parts of the 
fins dichotomise towards their terminations in the shorter rays ; posteriorly, 
this process creeps up towards their middle. The anterior margins of all the 
fins are set with prominent fulcra, which form a double row. 
The scales have not been quite accurately figured by Acassiz, whose artist 
(as is too often the case in the plates of the “ Poissons Fossiles”) has slurred 
over their salient peculiarities of form. Those of the body are arranged in the 
usual oblique or slightly sigmoidal dorso-ventral bands. Taking a scale from the 
front of the flank (Plate IIT. fig. 2), it is conspicuously higher than broad, though 
not so much so as in some other genera (Platysomus, Cheirodus, &c.). The 
anterior covered area is of considerable breadth, and marked off by a vertical 
groove from the exposed one, which is rhomboidal, the acute angles being 
posterior-superior and anterior-inferior ; the posterior margin is denticulated, 
or rather fimbriated, with fine sharp points, which, however, on some parts of 
the body, tend to pass into a coarse and prominent denticulation. The pointed 
articular spine or peg arising from the upper margin is of moderate size, and 
is quite distinct from the acute and upwardly produced anterior-superior angle 
of the scale. On the attached surface (fig. 3) a socket corresponding to the 
articular spine of the scale next below is seen at the lower margin, from which 
extending upwards to its own spine is an indication of the usual vertical keel. 
Towards the dorsal and ventral margins the scales become more equilateral, 
and that is also the case towards the tail, while they become at the same 
time more obliquely and regularly rhomboidal, and the keel of the attached 
surface more marked (figs. 5, 6). The scales of the sides of the caudal body- 
prolongation (figs. 8, 9) are acutely lozenge-shaped, and arranged in very — 
