Lign. 201. Fossil Fishes of the Devonian System.
(Drawn by Mr. Joseph Dinkel.)

Fig.1.—Pterichthys cornutus, seen from above.
2.—Coccosteus oblongus.

These figures are restored with great care, from the best preserved specimens hitherto discovered.

Coccosteus oblongus. [Lign. 201], fig. 2.—The fishes of this genus, as may be seen by the lignograph, very much resemble those of Pterichthys; in both the osseous scutcheons of the body are very similarly disposed. In Coccosteus, the head[546] is somewhat rounded; slight rounded notches on the edge of the buckler indicate the place of the eyes on the sides of the head. There is no indication of lateral spines. The tail is very long, covered with scales, and supports a fin. The plates of the body are tuberculated, as in Pterichthys. There are six or eight teeth on each half of the lower jaw (and probably as many on the upper), with a curious group of teeth situated on its symphisis. The teeth are chiefly composed of bone, passing into dentine at their surface.[547]

[546] This is of course only the cranial buckler of the animal, for, as Mr. Hugh Miller observes, "of the true internal skull there remains not a vestige. Like that of the Sturgeon, it must have been a perishable cartilaginous box."—Miller’s Foot-prints, p. 50.

[547] Miller, Rep. Brit. Assoc. 1850. Transact. Sect. p. 92. In the Annals of Natural History for November, 1848, Professor M‘Coy has given a corrected outline of the carapace, or bony cephalo-thoracic casing, of the Coccosteus. See also Miller’s Foot-prints, fig. 11.

These fishes are from a few inches to two feet in length; six species have been discovered; and their remains are the most abundant of the Ichthyolites of the Old Red. Patches of detached scales, and isolated osseous plates, are very frequent in the sandy cornstones, and the subcrystalline masses of limestone. These fragments are usually of a brilliant blue or purple colour; and, strongly contrasting with the dull red tint of the surrounding rock, are easily recognised. The colour is supposed to be due to the presence of phosphate of iron, which has communicated a similar tint to the Ichthyolites of the Caithness Schist.[548]