Fig. 31.—Fishes of the Devonian Epoch. 1. Coccosteus, one-third natural size. 2. Pterichthys, one-fourth natural size. 3. Cephalaspis, one-fourth natural size.
Among the Fishes of Old Red Sandstone, the Coccosteus ([Fig. 31], No. 1) was only partially cased in a defensive armour; the upper part of the body down to the fins was defended by scales. Pterichthys (No. 2), a strange form, with a very small head, furnished with two powerful paddles, or arms, like wings, and a mouth placed far behind the nose, was entirely covered with scales. The Cephalaspis (No. 3), which has a considerable outward resemblance to some fishes of the present time, was nevertheless mail-clad, only on the anterior part of the body.
Fig. 32.—Fishes of the Devonian epoch. 1. Acanthodes. 2. Climatius. 3. Diplacanthus.
Other fishes were provided with no such cuirass, properly so called, but were protected by strong resisting scales, enveloping the whole body. Such were the Acanthodes (1), the Climatius (2), and the Diplacanthus (3), represented in [Fig. 32].
Among the organic beings of the Devonian rocks we find worm-like animals, such as the Annelides, protected by an external shell, and which at the present day are probably represented by the Serpulæ. Among Crustaceans the Trilobites are still somewhat numerous, especially in the middle rocks of the period. We also find there many different groups of Mollusca, of which the Brachiopoda form more than one-half. We may say of this period that it is the reign of Brachiopoda; in it they assumed extraordinary forms, and the number of their species was very great. Among the most curious we may instance the enormous Stringocephalus Burtini, Davidsonia Verneuilli, Uncites gryphus, and Calceola Sandalina, shells of singular and fantastic shape, differing entirely from all known forms. Amongst the most characteristic of these Mollusca, Atrypa reticularis ([Fig. 33]) holds the first rank, with Spirifera concentrica, Leptæna Murchisoni, and Productus subaculeatus. Among the Cephalopoda we have Clymenia Sedgwickii ([Fig. 34]), including the Goniatites, illustrating the Ammonites, which so distinctly characterise the Secondary epoch, but which were only foreshadowed in the Devonian period.
Fig. 33.—Atrypa reticularis.