In the old red sandstone beneath the carboniferous beds in Scotland, scales and other remains of fishes were discovered many years since by Dr. Fleming, to whom I am indebted for the specimens before us. These scales belong to an extraordinary fish that has been named Cephalaspis (buckler-headed) by M. Agassiz, from the head being covered by a buckler or shield, and the bones united into one

Osseous case.

The scales form elevated bands, and of the fins are covered by the membrane

TAB. 137.-CEPHALASPIS LYELLII; LATERAL VIEW, SHOWING THE PRODUCED DORSAL LOBE OF THE TAIL.

which elsewhere surrounds them.

The fishes of

this genus bear a general resemblance in form to the large elongated trilobites of the Silurian rocks; they are confined to the old red sandstone system. They were first discovered by the eminent philo

that peculiar structure of the tail, which M. Agassiz states is found in almost all the fishes that occur in the formations below the saliferous system. In existing fishes, the fin of the tail presents itself in three forms; rounded and single (as in the macropoma, Tab. 61, fig. 2); in two symmetrical lobes (as in aulolepis, Tab. 61, fig. 2); and double with the dorsal portion prolonged, the vertebral column extending into the produced lobe (Tab. 135, a) as in the shark, dog-fish, &c. It is this last form, which

In the old red sandstone beneath the carbonferous beds in Scotland, scales and other remains of fishes were discovered many years smee by De Fleming, to whom I am indebted for the specimens before us. These scales belong to an extratimey fish that has been named Cephalosqus buctaer-heater by M. Agassiz, from the head being overet og a buckler or shield, and the bones mined mu m

Osseous case.

The scales form elevated hands, and of the fins are covered by the meNNAIE

TAB. 137.-CEPHALASPIS LYELLII; LATERAL VIEW HEIVE I PRODUCED DORSAL LORE OF THE TAIL

By M. Agassiz.)

rounds them. The files of eral resemblance in form to obites of the Silarian rocks; e old red sandstone system. ered by the eminent philo.

sopher whose name is attached to the principal species,* at Glammis, in Forfarshire; they occur also in Shropshire, Herefordshire, and other districts of England and Wales; and Mr. Murchison has traced their remains throughout the old red system of England and Scotland. The enormous size of the head, its crescent-like shape, terminating in two lateral horns or processes, and its lamellar structure, form so striking a resemblance to the shells of crustacea, that it is not surprising that disjointed portions should have been often mistaken for the remains of trilobites (Tab. 136, 137).

Another remarkable group of fishes, of these strata, is the sauroid, of which several gigantic species have been found by Dr. Hibbert, in the strata of Burdie-House. The teeth of these fishes are large striated hollow cones, bearing considerable resemblance to the teeth of crocodiles, with which

they were formerly confounded. The scales are thick and strong. The tail, as in the fishes above described, is unequal, the vertebral column extending to the extremity of the upper or dorsal lobe. But I must not dwell longer on this division of our subject; the work of Mr. Murchison, which I have so often cited, and again shall repeatedly have occasion to notice, must be referred to for a more ample account of the ichthyolites of the carboniferous and Devonian systems.†

Principles of Geology, fifth edition, vol. iv. p. 296.
Silurian System, vol. ii. p. 585 to p. 601

ANCIENT WORLD.-In conclusion, let us review the botanical characters of the geological formations, as

(Drawn by Miss Ellen Duppa.)

Fig. 1. Voltzia longifolia. 2. Voltzia brevifolia, with the fructification. 3. Filicites Scolopendroides.

indicated by the fossil vegetables hitherto discovered. In the transition rocks, hereafter to be described,