IG 



BRITISH FOSSILS. 



account of the striking analogy of its general physiognomy, and of 

 the form, arrangement, and structure of its fins, adds : "I must 

 " admit that side by side with these resemblances, the tv/o types 

 " exhibit profound differences," ..." which will perhaps, in 

 " the long run, necessitate another arrangement.'' 



The idea that Coelacanthus inclined more to Holoptychius than 

 to Maeropoma, appears to have found still more favour with Pro- 

 fessor Agassiz at the time of the publication of his great work on 

 the Fishes of the Old Red Sandstone ; and the consequences of this 

 inclination were the more important from the fact, that Agassiz 

 held that the teeth, properly distinguished by Professor Owen 

 under the name of Rhizodus, belonged to Holoptychius. For 

 Glyptolepis and Platygnatlms were undoubtedly closely allied to 

 Holoptychius, while Dendrodus, Lamnodus, and Gricodus had 

 much in common with Rhizodus ; hence, as these dendrodont teeth 

 were conceived by Agassiz to belong to the fish whose bony plates 

 and scales had received the names of AsterolepiSy Bothriolepis, &c., 

 it was natural that he should include all these genera under the 

 common title of" Coelacanths ;'' while lfacroj9oma and UndinawerQ 

 regarded with doubt, and, in fact, almost excluded fi-om the group 



Vieux Ores Rouge," p. 64). 



Here, however, I cannot but believe, that the founder of fossil 

 ichthyology has, for once, gone off' upon a wrong scent. For 1 iier 

 investigations have made it, to say the least, extremely improbable 

 that Asterolepis (Ag. & Miller) has anything to do with Gricodus, 

 or with Holoptychius, whatever may be the relation of the two 

 latter genera ; and I shall now endeavour to prove that, while 

 Goelacanthus is so intimately connected with Undina and Maero- 

 poma, as to render the generic distinction of the three forms a matter 

 of minute detail, its relations with Holoptychius, although clear and 

 distinct so far as they go, are, at most, those of a member of the 

 same suborder. 



But first, what are the characters of the genus Godacanthus ? 

 This question is by no means so easily to be answered as might be 

 imagined, but the following facts appear to furnish a conclusive 

 reply to it. 



The type species of Godacanthus, that on which the genus was 

 founded by Agassiz, is the G. granulatus of the Magnesian Lime- 

 stone ; two figures of which are to be found in the " Recherches," 

 while a third, representing another specimen, is given by Sir Philip 

 Egerton in King's Permian Fossils." Singularly enough, neither of 

 these specimens retains its head, nor are the paired fins preserved ; 



