1866..
YOUNG CAllBONIFEROFS GLYPTODir TERINES.
597
lated by similar anastomosing ridges. The pectoral arch is well
developed, and supports a subacutely lobate fin with rounded margin.
The two dorsals, the ventrals, and anal are of nearly equal size, and
opposite each other respectively. The tail is heterocereal and
rhomboidal.
Figs. 1-8. — Illustrating the teeth and scales of some new genera of
Carhoniferous Fishes.
Fig. 1. Rhomboptychius, tooth.
2. Rhomboptychius, scale.
3. Strepsodus, tooth.
4. E.hizodus, scale.
Fig. 6. Rhizodus, tooth.
6. Megalichthys, scale.
7. Dendroptychius, scale.
8. Rhizodopsis, scale.
The scales vary somewhat in size and shape on different parts of
the body ; they are arranged in very oblique series, and range from
nearly orbicular to elongate cordate. The upper surface is orna-
mented with concentric and radiating striae; the latter are most
strongly marked over two triangular areas whose bases correspond
to the centre of the anterior and posterior margins respectively ; the
former occupy the lateral surfaces between those areas. The under
surface is marked by more or less numerous growth-lines, presents
a subcentral raised boss, and is usually pitted over a small area
immediately behind the centre ; no corresponding tubercles are visible
on the upper surface, whose free area averages two-thirds of the
whole surface. The lateral line is well marked and nearly straight.
The notochord is persistent ; the osseous rings surrounding it are
short and narrow. The upper arches are distinct and well ossified.
These characters are in the main those of the family to the cycloidal