DEVONIC FISHES OF THE NEW YORK FORMATIONS 9 1 



a single group.' This assemblage was modified a twelvemonth later, how- 

 ever, in that the two last named divisions were bracketed together under 

 the head of " Temnauchenia," all of the others, together with Drepanaspids, 

 Coelolepids and Birkeniidae, being collectively designated as " Holau- 

 chenia."' Placoderms in this broadened sense were all considered by 

 Jaekel to belong to fishes proper, and it was further maintained by him 

 that Coccosteans were ancestral to Chimaeroids, an opinion in which he 

 clearly stands alone. The only other author who has ventured to recognize 

 any descendants from Arthrodires whatever is Newberry, who, as we have 

 seen, imagined Protopterus to be a modern survival of Dinichthys. 



We may now pass rapidly in review the minor fluctuations of opinion 

 that are apparent during the last few years. Dr O. P. Hay, in his Cata- 

 logue of Fossil Vcrtcbrata of North America, employs the term Placodermi 

 for both Arthrodires and Asterolepids, placing them in the same subclass 

 with Dipnoans. Arthrodires and Ostracophores are awarded each the rank 

 of a separate subclass in the English edition of von Zittel's Textbook of 

 Palaeontology, the author having disapproved of an association between 

 Coccosteans and Dipnoans. In Mr C. T. Regan's remarkable paper of 

 1904, already referred to, the Placodermi are reestablished so as to include 

 Coccosteidae, Asterolepidae and Cephalaspidae, all being united in a single 

 order of Teleostomes.^ During the same year Professor Bridge expressed 

 the view, in the volume on Fishes in the Cambridge Natural History, that 

 Coccosteans are " a highly specialized race of primitive Teleostomi," and 

 compared their cranial roofing plates with those of typical bony fishes. The 

 idea of a relation between them and lung fishes is dismissed in the follow- 

 ing passage, found at page 537 of the work in question : 



The Arthrodira have been regarded as armored Dipneusti, a view 

 which is mainly based on their supposed autostylism and the nature of the 



^Jaekel, O. Ueber Coccosteus und die Beurcheilung der Placodermen. Sitzungsber. 

 Gesellsch. Naturforsch. Freunde. 1902. p. 103. 



"^Idcrii. Ueber die Organisation und systematische Stellung der Asterolepiden, 

 Zeitschr. deutsch. geol. Gesellsch. Mai-Protokoll. 1903. 55:58. 



3 Regan, C. T. The Phylogeny of the Teleostomi. Mag. Nat. Hist. Ann. ser. 7, 

 1904- 13:346. 



