Traquair). I had long suspected that a very beautiful species from Burdiehouse was identical with the P. ornatissimus, Agassiz; and a few days ago I obtained two of the original specimens of that species, and found that one of them, at least, certainly confirmed my opinion. It is the type of a group including P. carinatus, Ag., a species described from a very imperfect specimen from the Wardie shales now in the museum of the Royal Society of Edinburgh. Examples in a much better state of preservation, however, have subsequently turned up in the same locality. The body is slender, elegantly shaped; the scales are rather large, especially on the flank; the median fins are large in proportion to the size of the fish; the dorsal is situated nearly opposite the anal; the caudal body-prolongation is delicate. I have had no satisfactory view of the dentition or of the structure of the pectoral fin in this species; but its general aspect leads me to class it along with the Palæoniscus ornatissimus, Ag., and Palæoniscus Wardii, of Prof. Young, recently briefly described by Mr. Ward, of Longton[1], as constituting a new genus, Rhadinichthys. The characters of generic importance displayed by the two last named species are as follows:—The body is comparatively slender; the suspensorium is very oblique; the jaws are armed with a row of incurved conical laniaries, outside which there is a series of smaller teeth; the principal rays of the pectoral fin are, as in Pygopterus and Oxygnathus, unarticulated till towards their terminations; the dorsal is situated rather far back, nearly opposite the anal; the caudal body-prolongation is comparatively delicate. There are, besides these, several other new species from British Carboniferous strata referable to this type, the description of which I hope soon to be able to overtake; in some of these the scales are nearly smooth, as in R. carinatus, in others elaborately ornamented.
Palæoniscus Albertii, of Jackson, seems to me to be allied to R. carinatus; but more especially so, judging from the drawings, is his P. Cairnsii, and some of the other small Palæoniscidæ from the Coal Measures of New Brunswick, figured, but not described, by the same author[2]. All the species which I propose to include under Rhadinichthys are from Carboniferous strata.
The three remaining types included by Agassiz in Palæoniscus must be altogether excluded from the family Palæoniscidaæ.
V. Type of Palæoniscus fultus, Ag. (Genus Ischypterus, Egerton). This Triassic species, in which the caudal body-prolongation is considerably more reduced than in the Palæoniscidæ, the tail consequently showing the first approach to the semiheterocercal form, and whose general structure, including the osteology of the head, betrays a strong affinity to Semionotus, has been already separated by Sir Philip Grey-Egerton under the name of Ischypterus[3]. Besides Ischypterus fultus, Ag., sp., there are here included I. Agassizii, I. macropterus, I. latus (=Eurynotus tenuiceps, Ag.), and
