238 Dr. R. II. Traquair on the Structure 



the structure of tlic true Acanthodida3 have long since shown 

 tliat this generalization was rather hastj. Cheiroh'])is, how- 

 ever, lie considevoJ as forming, by tlic absence of spiny rays 

 to the tins and by its unequal dentition, the " passage of the 

 Acanthodians to the Sauroids." 



Although the restored figure of Chnrolepis given by Agassiz 

 in the ' Poissons Fossiles du vieux Grbs Kouge,' tab. D. tig. 4, 

 is quite erroneous as regards the shape of the maxilla and of 

 the opercular bones, he having eviaently supj)0.sed that the 

 bones of the head were conformed much as in the recent 

 8almonidw, yet as regards his assertion of the jiresence of 

 branchiostegal rays and of an unequal dentition (facts after- 

 wards questioned by others) he was undoubtedly right. 



Our own countryman Hugh ]\Iiller, however, was shrewd 

 enough to be impressed with the discrepancy of structure in 

 CltciroUpis and the Cheiracanthi and Diplacanthi^ witli which 

 it had been classed ; and accordingly we find him, in his ' Old 

 Red Sandstone,' mentioning it as the type of a distinct family. 

 Nor did these discrepancies escape the attention of Johannes 

 Miiller, as may be seen from a brief passage in his paper 

 " Ueber den Bau und die Grenzen der Ganoiden"*. By 

 Giebelf it Avas also disassociated from the Acanthodians and 

 classed amongst his " Ilcterocerci Monopterygii," a group un- 

 fortunately nearly as heterogeneous as Agassiz's " Lepidoides." 

 Nevertheless for years afterwards many eminent palaeontolo- 

 gists (such as Pictet|, Quenstedt§, M'Coyll, and Sir Philip 

 EgertonU) continued to class Cheirolepis along with the 

 Acanthodidffi. 



Pander, however, in one of his justly celebrated essays on 

 the Devonian fishes**, entered into the structure of Clieirole'pis^ 

 and proposed to constitute for it an independent family, the 

 Cheirolepini. Many of its head- and shoulder- bones were 



* Abhandl. der Berl. Akad. 1844, Phys. Kl. p. 161. 

 t ' Fauna der Vorwelt,' 1848, vol. i. p. 2.31. 



I 'Traite de Palt3ontolo{?ie,'2rae ^d. t. ii. p. 190. 



§ ' Ilandbuch der Petrefactenkunde ' (18.52), p. 192. That Quenstedt 

 was nevertheless rather doubtful on this point may be inferred from the 

 follo\viug passage, in his description of the Acanthodidse : — " Xur CJiei- 

 rolepis hat Fulcra an alien Flossen, und auf dem Riicken des Schwanzes ; 

 dennoch halt ihn Agassiz auch fiir einen Acanthodier. Miigen auch alle 

 diese Fische (aiisser Cheirolepis) den Icbenden Haien sich nicht unmittelbar 

 anschliessen, so stehen sie ihnen doch gewiss naher als den folgenden 

 Ganoiden." 



II 'Palajozoic Fossils,' p. 580. 



il " Remarks on the ?s omenclature of the Devonian Fishes," Quart. 

 Journ. Geol. Soc. xvi. p. 12.3. 



♦* ' Ueber die Saurodipterinen, Dendrodonten, Glj'ptolepiden, und Chei- 

 rolepiden des devonischen Systems,' St. Petersburg, 18G0, pp. 09-73. 



