Fig. 23.
SECTION OF VERTEBRAL CENTRUM OF THORNBACK.
[18] One of the Thurso coprolites in my possession is about one fourth longer than the larger of the two specimens figured here, and nearly thrice as broad.
[19] In two of these, in a collection of several score, I have failed to detect the spiral markings, though their state of keeping is decidedly good. There are other appearances which lead me to suspect that the Asterolepis was not the only large fish of the Lower Old Red Sandstone; but my facts on the subject are too inconclusive to justify aught more than sedulous inquiry.
[20] The shaded plate, (a,) accidentally presented in this specimen, belongs to the upper part of the head. It is the posterior frontal plate F, which half-encircled the eye orbit, (see fig. 29;) and I have introduced it into the print here, as in none of the other prints, or of any other specimens, is its upper surface shown.
[21] The late Mr. John Thurston.
[22] “Mr. Phillips proceeded to describe some remains of a small fish, resembling the Cheiracanthus of the Old Red Sandstone, scales and spines of which he had found in a quarry at Hales End, on the western side of the Malverns. The section presented beds of the Old Red Sandstone inclined to the west; beneath these were arenaceous beds of a lighter color, forming the junction with Silurian shales; these, again, passing on to calcareous beds in the lower part of the quarry, containing the corals and shells of the Aymestry Limestone, of their agreement with which stronger evidence might be obtained elsewhere. He had found none of these scales in the junction beds or in the Upper Ludlow Shales; but about sixty or one hundred feet lower, just above the Aymestry Limestone, his attention had been attracted to discolored spots on the surface of the beds, which, upon microscopic examination, proved to be the minute scales and spines before mentioned. These remains were only apparent on the surface, whilst the ‘fish-bed’ of the Upper Ludlow rock, as it usually occurred, was an inch thick, consisting of innumerable small teeth and spines.”—Report, in “Athenæum” for 1842, of the Proceedings of the Twelfth Meeting of British Association, (Manchester.)
[23] “This is the lowest position” (that of the Onondago Limestone) “in the State of New York in which any remains have been found higher in the scale of organized beings than Crustacea, with the exception of an imperfectly preserved fish-bone discovered by Hall in the Oriskany Sandstone. That specimen, together with the defensive fish-bone found in this part of the New York system, furnishes evidences of the existence of animals belonging to the class vertebrata during the deposition of the middle part of the protozoic strata.”—American Journal of Science and Arts for 1846, p. 63.
[24] “The shales alternating with the Wenlock Limestone.” (Edinburgh Review.)