Strüver, from the Keuper Sandstones of Coburg[1], for an opportunity of examining actual specimens of which I am indebted to the kindness of Prof. von Seebach, of Göttingen. Until therefore the cranial osteology and the dentition of these forms is better known, I would propose that the Palæoniscus catopterus of Agassiz be included in the genus Dictyopyge of Sir Philip Grey-Egerton. Of the closeness of the alliance there can be hardly a doubt; so that the relationship of this little fish to the American Triassic genus Catopterus is not so distant as has been supposed[2].
Gyrolepis.
In the "Tableau synoptique des genres et des espèces," given at the beginning of the second volume of the 'Poissons Fossiles,' this genus is referred to in the following terms:—
"Le genre Gyrolepis, Agass., n'étant établi que sur quelques écailles, est encore douteux. Ce qui le distingue, c'est que les stries d'accroissement forment des saillies concentriques à leur surface." Three Triassic species are here included, viz. G. maceimus, Ag., G. tenuistriatus, Ag., and G. Albertii, Ag., along with one from the Kupferschiefer, G. asper, Ag. Further on in the same volume (p. 172), in a more special description of the genus, Agassiz again owns that, having found only detached fragments, non-coherent scales, and even these rarely entire, the special characters of the genus are not satisfactorily established. Meanwhile, he says "l'aspect de ces écailles est tel, qu'il serait impossible de les rapprocher d'aucun des genres que j'ai déja décrits. La surface extérieure des écailles est ornée de grosses rides, tantôt concentriques et parallèles aux lames d'accroissement, tantôt obliques et irrégulièrement ramifiées. J'ai cru pendant quelque temps que ces rides étaient toujours concentriques; mais plus tard je me suis assuré qu'elles étaient souvent aussi disposées en peignes irrégulières." Certain dentigerous fragments found along with the scales are also, with some doubt, referred to the same genus; the teeth on them are described as being small and "en forme de cônes obtus dont l'extrémité est arrondie, et qui sont disposées comme dans la famille des Pycnodontes
- ↑ Zeitschr. der deutschen geol. Gesellsch. xvi. 1864, pp. 303–330, pl. xiii.
- ↑ The genus Dictyopyge was separated from Catopterus of J. H. Redfield by Sir Philip Grey-Egerton on account of the supposed heterocercal nature of the tail in the latter. I hope, however, that I shall not be deemed wanting in respect to the high authority of our greatest English writer on fossil ichthyology in pointing out that not only is the semiheterocercal nature of the tail in Catopterus distinctly asserted in Mr. J. H. Redfield's original description and borne out by his figure (Ann. Lyc. Nat. Hist. N. York, iv. 1848, pp. 35–40, pl. i.), but also reaffirmed by Mr. W. C. Redfield, who therefore proposed to cancel Dictyopyge, recalling D. macrura as a Catopterus (Proc. Am. Assoc. Albany, 1856, pp. 180–188). But, as in the typical Catopterus gracilis, J. H. Redf., the dorsal fin is situated still further back than in the species macrurus, W. C. Redf., socialis, Strüver, or in the little catopterus of Agassiz, the genus Dictyopyge may, I think, be advantageously retained for these last-named forms.
