Note 46 — Chapter VII

The above descriptions of the scales and teeth of these two fishes, are taken from specimens in my own collection. None of my holoptychian scales show incontestable the proportion of the covered to the exposed part. Judging from the aspect of one of them, the wrinkled portion occupied perhaps about three-fifths of the entire scale, the remaining part being covered by the overlapping edges of those adjacent; for the characteristic corrugated surface was essentially an external ornament, and ceased at the point where the external bone passed into the interior. I may remark, that the upper side of the scales is not very frequently seen in the Burdiehouse limestone, the rough surface usually adhering to the rock, and leaving only the smooth inner side exposed. Out of seven specimens from that locality, only one shows the upper side, and that by no means in a perfect state of keeping. The structure alike of scales and bones can be seen to much greater advantage in the shales, ironstones, and coals of the coal-fields, where, owing to the soft nature of their matrix, the fossils can be readily cleared and exposed.