File:The Quarterly journal of the Geological Society of London (12960135993).jpg

CANCEL COAL OF THE "WEST EIDI:s:G OP YOBKSHIBE.
63
surface is ornamented by a series
of longitudinal striations. On
the posterior surface there is a
single row of denticles, extending
from the apex 2 or 2-5 inches to-
wards its base. The denticles are
broad at the base along the longi-
tudinal axis, their sides are com-
pressed, and they terminate ob-
tusely ; eight of the denticles and
intermediate spaces are contained
in the space of 1 inch. The spine
is somewhat flattened, and presents
an oval section ; but this is pro-
bably due to compression, and the
spine may originally have been
nearly or quite circular. There
is an internal cavity, which is ter-
minal at the basal extremity and
extends almost to the point ; the
cavity is central, and large in com-
parison to the diameter of the
spine.
Many of the Siluroid and Cy-
prinoid fishes of the fresh waters
of India bear on the anterior por-
tion of the first dorsal fin a bony
ray or spine, which is frequently
ornamented or armed with a row
of denticles along its posterior mar-
gin. Among the Cyprinoids may
be mentioned the Scliizotliorax ;
and in a species of Siluroid,
Macrones vittatus^ Bl., kindly sent
to me by Mr. Francis Day, and
collected by that intrei3id natural-
ist in one of the rivers of Northern
India, there are one dorsal and
two pectoral fins, protected by
sjjines ; these present a close ex-
ternal resemblance to the spines of
Compsacanthus from the Coal-
measures of West Yorkshire. The
Macrones is a small fish, about 5
inches long ; its head is covered
with a number of bony plates,
whilst the body is devoid of scales.
It has two pectoral and two ven-
tral fins, and an anterior and pos-
terior dorsal fin. All except the
to
g.
.2.