BRITISH FOSSILS. 



Decade the Tenth. 



Pkeliminary Essay upon the Systematic Areangement of the 

 Fishes of the Devonian Epoch, by Thos. H. Huxley, F.RS., 

 Professor of Natural History, Government School of Mines. 



The endeavour to determine the systematic position of Glypto- 

 Icemus, a genus of Devonian fishes, first described and figured in 

 Dr. Anderson's interesting work upon Dura Den,"* and more fully 

 discussed and illustrated in the course of the present Decade, has 

 gradually led me to reconsider the whole question of the classifica- 

 tion of the fishes of this epoch and, eventually, to arrive at results 

 which seem to necessitate an important modification of the received 

 arrangement of the great order of Ganoid ei. 



I propose, in the course of the pages of this preliminary essay, to 

 take the reader through the various steps of the argument which 

 terminates in this conclusion ; and, commencing with a brief enu- 

 meration of the most important characters of Glyptolcmms, I shall 

 proceed to the discussion of the peculiarities of other genera, more 

 or less nearly allied to it, with the view of demonstrating, finally, 

 that Glyptolmmus is a tolerably typical member of a large and well 

 defined family of Ganoids, which abounded in the Devonian epoch, 

 but whose members have been less and less numerous in more 

 modern formations, until, at present, its sole representative is the 

 African Polypterus. 



Fia 1. 



Restoration of Glyptolccmus. 



Glyptolcemus KiQinairdi (fig. 1, and Plates I. and II.), the only known 

 species of its genus, is a fish with an elongated body, a depressed head, 



* Dura Den; a Monograph of tlie Yellow Sandstone, and its remarkable Fossil 

 Remains. 1859. 



10 A 2 



