PAL.EONISCUS, GYROLEPIS, AND PYGOPTERUS. 567 



Struver, from the Keuper Sandstones of Coburg *, for an oppor- 

 tunity of examining actual specimens of which I am indebted to the 

 kindness of Prof, von Seebach, of Gottingen. Until therefore the 

 cranial osteology and the dentition of these forms is better known, 

 I would propose that the Palceoniscus 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 f . 



Gyrolepis. 



In the " Tableau synoptique des genres et des especes," 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'etant etabli que sur quelques 

 ecailles, est encore douteux. Ce qui le distingue, c'est que les stries 

 d'accroissement forment des saillies concentriques a leur surface." 

 Three Triassic species are here included, viz. G. maceimus, Ag., G. 

 tenuistriotus, 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 

 ecailles est tel, qu'il serait impossible de les rapprocher d'aucun des 

 genres que j'ai deja decrits. La surface exterieure des ecailles est 

 ornee de grosses rides, tantot concentriques et paralleies aux lames 

 d'accroissement, tantot obliques et irregulierement ramifiees. J'ai 

 cru pendant quelque temps que ces rides etaient toujours con- 

 centriques ; mais plus tard je me suis assure qu'elles etaient souvent 

 aussi disposees en peignes irregulieres." Certain dentigerous frag- 

 ments 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 cones obtus dont Textremite est 

 arrondie, et qui sont disposees comme dans la famille des Pycnodontes 



* Zeitschr. der deutschen geol. G-esellsch. xvi. 1864, pp. 303-330, pi. xiii. 



t 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 re- 

 spect 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. Lye. Nat. Hist. N. York, iv. 1848, pp. 35-40, pi. 

 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, Struver, or in the little catopterus of Agassiz, the genus 

 Dictyopyge may, I think, be advantageously retained for these last -named 

 forms. 



Q. J. G. S. No. 131. 2p 



