REPORT OF FOSSIL FISHES, 27 
the size of the specimen, from 4 to 7 longitudinal elevations or feeble ridges 
running across the scale with a slight downward obliquity, as well as a 
slight tendency to radiation, and ending on as many sharp denticulations of 
the hinder margin. Towards the back and belly (fig. 18) both sets of markings 
tend to become confounded into one set of delicate, more or less diagonal ridges 
and grooves, and towards the tail (fig. 17) these markings usually fade away ; 
a few punctures and longitudinal furrows being in most cases all that is to be 
seen on the scales behind the dorsal and anal fins. In different individuals, 
however, very considerable differences are found as regards the strength and 
prominence of the scale-markings. In some the markings are very distinctly 
and sharply defined (fig. 15), and the scales continue to be highly ornate up 
to the caudal body-prolongation, while in others (fig. 16) even those on the 
front part of the body are comparatively smooth, the middle of the scale 
being marked with a few short grooves, and the oblique ridges becoming 
apparent only towards the posterior margin; a reference to the figures 
will, however, give a better idea of the variations in the general aspect of 
the scale sculpture than any amount of description. 
The pectoral fin is rather smail, its length being hardly more than half 
that of the head; the larger rays on the preaxial aspect are unarticulated 
till towards their terminations. The ventrals are small and delicate, and not 
well exhibited in any of the specimens. The dorsal fin commences only very 
slightly in front of the anal, the two fins being thus placed nearly opposite 
each other; they are very similar in shape and structure, being moderate in 
size, acuminate, concavely cut out behind, and composed of delicate rays, 
which dichotomise towards their extremities, are distantly articulated, and 
having their brilliantly ganoid jomts marked usually by a single sharp 
longitudinal furrow, though even this is sometimes wanting save near the 
origin of the fin. Between the anal fin and the commencement of the lower 
lobe of the caudal is an interval fully equal to the length of the base of the 
former. The caudal is also moderate in size, deeply bifurcated, and with a well- 
developed body-prolongation along the upper lobe ; its rays partake of the same 
general appearance as those of the dorsal and anal, though their articulations 
are a little closer, and their surfaces usually quite smooth. Delicate fulcra 
are observable in the anterior margins of all the fins. 
Var. elegantulus (Pl. II. figs. 1-5).—Length 23 to 23 inches, elegantly fusi- 
form, general proportions as in the foregoing, but the cranial roof bones are 
ornamented with closely set rounded ridges, which are proportionately some- 
what coarser, and more contorted in their arrangement ; in one very perfect 
specimen, in which the head bones are beautifully exhibited, the maxilla is 
destitute of tuberculation along its inferior margin. The markings on the scale 
are faint, those on the sides and belly being nearly smooth; their posterior 
