since some of the species are confined to the Triassic period"[1]. Subsequently, however, Sir Philip expressed an opinion that in Gyrolepis "we have probably a heterocerque fish"[2].
More recently Dr. Karl Martin has advocated the view that the Triassic scales known as Gyrolepis belong to Saurichthys, "because the strongly marked sculpture of their surface (like the condition of the teeth of Saurichthys) reminds us of that of the scales of Acrolepis, and because hitherto neither teeth have been found which could correspond to these scales of Gyrolepis, nor other scales which could be ascribed to the teeth of Saurichthys." Saurichthys itself is referred by Martin to the family Palæoniscidæ on account of the resemblance which the teeth and a fragment of a maxilla figured by him bear to those of Acrolepis asper[3].
Finally, as I have already mentioned (p. 550), Prof. Victor Carus has not only reunited Rhabdolepis, Troschel, to Amblypterus, Ag., but has added, as synonyms of the latter, Gyrolepis, Colobodus, and Tholodus. I need not again point out how inconsistent it is with the prevailing ideas of the limits of a genus to reckon as congeneric with such a fish as Amblypterus latus scales like those known as Gyrolepis, or teeth like those of Colobodus or Tholodus.
From the preceding sketch of its history it is abundantly clear that at present all definition of Gyrolepis as a genus is impossible; and under the circumstances it does seem to me better to follow the example of Giebel in cancelling the term altogether. As regards the Triassic species which have been so named, I must necessarily leave the final determination of their position to continental palæontologists. But, as to the use of the name Gyrolepis in catalogues of British Carboniferous fossils, there can, I think, be no doubt as to the propriety of its entire abolition; for, unless the Triassic scales to which the name was originally given are really referable to Acrolepis, there is no Carboniferous fish of which we have the smallest evidence that it belongs to the same genus with them. What, then, is the real nature of the one Carboniferous species which has been definitely named Gyrolepis, but which has hitherto remained undescribed?
The name Gyrolepis Rankinei occurs in Agassiz's general list of fossil Ganoids, the formation and locality quoted being the Coal- measures of Leeds. Neither description nor figure is given; and the original specimen seems now, unfortunately, to be lost or unknown. But in Morris's 'Catalogue of British Fossils ' (p. 273) Lanarkshire is given as an additional locality for this species; and on inquiring of Dr. Rankin, of Carluke, and Mr. Grossart, of Salsburgh, in that county, I learn that Agassiz, when in Scotland, also designated as G. Rankinei a specimen in Dr. Rankin's collection. To these gentlemen I am indebted for the opportunity of examining portions of the original Lanarkshire specimen, along with others
