156 Proceedings of the Royal Physical Society. 



nificently delineated, but we shall see that he was not quite 

 so successful in his conception of his family of "Dendrodonts," 

 from which he excluded Holoptychius and Glyjptolepis, making 

 the latter indeed into the type of yet another distinct family. 

 From his elaborate and truly scientific researches, Pander 

 derived one interesting generalisation, which presently rose 

 to extreme importance. Johannes Mtiller had long before 

 shown that the recent Lepidosteus and Polypterus, classed 

 together by Agassiz in one family, that of the so-called 

 Sauroidei, were representatives of totally distinct groups of 

 Ganoids; but among all the fossil fishes of the order, he 

 could for Polypterus find no ally. Pander, however, pointed 

 out that, far from Polypterus having no ally in past ages, it 

 is to it rather than to Lejpidosteus that the affinities of many 

 of the Old Eed Sandstone Ganoids point, and more especially 

 those of the group known as Saurodipterini. 



The researches of Pander were soon afterwards brilliantly 

 followed up by the publication, in 1861, of Professor Huxley's 

 masterly "Essay on the Systematic Arrangement of the 

 Fishes of the Devonian Epoch." Huxley had already, in 

 1858, published observations on the genera Cephalaspis and 

 Pteraspis, and the Eev. Dr Anderson's " Monograph " of the 

 Yellow Sandstone of Dura Den and "its remarkable fossil 

 remains," which appeared in 1857, is rescued from oblivion 

 and contempt by its including descriptions, furnished by 

 Huxley, of the new genera Glyptolmmus and Phaneroplettron, 

 with observations on the genus Holoptychius. The study of 

 these interesting forms led Professor Huxley to re-examine 

 the whole subject of the classification of the Ganoids, and 

 especially of those of the Old Eed Sandstone, and his results 

 appeared in the essay above quoted, which forms part of the 

 Tenth " Decade " of the Geological Survey. 



Pander, we have seen, noticed the fact that many of the Old 

 Eed Sandstone Ganoids were more allied to Polypterus than to 

 Lepidosteics. Huxley, proceeding farther in the same direction, 

 instituted the sub-order Crossopterygidce, of which Polypterus 

 and Calamoichthys are the sole living representatives, but which 

 in palaeozoic times included an extensive assemblage of forms, 

 collectively equivalent to Agassiz's Coelacanthi and Saurodip- 



