118 GANOID FISHES OF 'THE CARBONIFEROUS FORMATION. 
in fig. 5 of this Plate, is finely tuberculated. ‘lhe mandible is composed of four pieces 
at least—the dentary, articular, angular, and splenial. The dentary is represented 
isolated in Pl. XXVI, fig. 6 ; it is elongated but strong, and is slightly bent upwards 
at its anterior extremity ; its external surface is beautifully and closely tuberculated, 
the tubercles being sometimes longitudinally elongated into short ridges, ‘I'he splenial 
element is shown, detached, in Pl. I, fig. 10; the position of the angular (ag.) and 
articular (a7.) in figs. 9 and 11 of the same Plate. 
The palatoquadrate apparatus is elongated and concave externally, like that of other 
Paleoniscide. It certainly consists of several pieces—of three and probably also of a 
fourth—but my material is not yet sufficiently perfect to enable me to give a definite 
figure and description of the arrangement. 
‘Teeth occur on the dentary element of the mandible and on the maxilla and pre- 
maxilla, but, so far as I can see, zof on the splenial or on the hard palate. ‘They are, 
as usual, of different sizes, the small ones being more externally placed than the large or 
“Janiaries”’; they are sharp, conical, enamel-capped, slightly incurved, smooth on the 
outer side, while the inner one is slightly striated ; the pulp cavity is very roomy at the 
base (Pl. XXVI, fig. 7). 
‘The scales, as noted in the generic diagnosis, are peculiar in form (figs. 9—11). All 
along the back and flanks they are much higher than broad ; the exposed area is indeed 
more or less rhomboidal, but the acute angles are here the postero-superior and the 
antero-inferior. ‘The antero-superior angle is not produced into a point, distinct from 
the proper articular peg, or spine, which latter, broad and triangular (fig. 9), arises from 
the entire upper margin of the scale. ‘I'he exposed ganoid surface is ornamented by 
very delicate thread-like wavy ridges, branching and intercalated, which on the scales of 
the flank are subparallel and run more or less vertically down the scale, or between the 
two acute angles (fig. 9); on the scales of the back, however, they often follow a more 
irregular and flexuously contorted course (fig. 11). On the under or attached surface 
of the scale the usual keel is obsolete. 
On the ventral surface of the body the scales are very small and so low as to appear 
equilateral ; all the scales, however, appear to have the same ornamentation, consisting 
of fine wavy ¢hread-like ridges, whence the generic name Nematoptychius. 
The elements of the shoulder girdle are conformed as in other Paleeoniscide, and do 
not call for special description. 
The pectoral fin is not shown in the fine example represented in Pl. XXVI, fig. 1, 
but in fig. 8 we have a good view of it, all except the apex, which is cut off by the edge 
of the stone—another specimen, not figured, shows, however, that this fin was pointed 
distally. Fig. 8 shows well the condition of the principal rays as to transverse articula- 
tion, the first joint of each of these rays being much larger than those which succeed. 
The ventral fin of the right side is shown in fig. 1, its extremity being cut off, like 
those of the other fins of this specimen, by the edge of the nodule. ‘I'he base is rather 
