XXIV 



to the knowledge of the natural families of fishes, somewhat modified, and 

 published in the extended memoir which appeared in the Transactions 

 (Abhandlungen) of the Society. 



The memoir, as finally published in the Abhandlungen, contained addi- 

 tional details (on pp. 118, 126 to 129, physiological observations on the 

 bulbus arteriosus; 1 pp. 154 to 195, Abschnitt II. fiber die naturlichen 

 Ordnungen und Familien der Knochenfische 9 ) ; the paragraphs on the 

 Apodes, Esoces, Galaxiae, and Clupesoces in the Archiv (pp. 131-134) 

 were omitted, and a postscript (Nachschrift, pp. 204-208) was added 

 containing the results of subsequent observations, and especially remarks 

 on the genus Amia and Carl Yogt's researches thereon. This postscript 

 was, in many respects, a reproduction of an article published in the Mo- 

 natsberichte. 



The memoir next in importance from the great light which was shed 

 upon many obscure questions of Palaeichthyology was contributed by 

 England's great naturalist, Prof. Huxley. 8 In the article in question, 

 though professedly upon the Devonian fishes, all that could render intel- 

 ligible the forms treated was called into requisition, and many unexpected 

 relations were demonstrated or approximated. 



The discovery of a representative of the Ceratodontids, a type previously 

 supposed to have become extinct in the triassic epoch, was the next event 

 of importance ; the most sagacious recognition of its affinities, evidence of 

 extended knowledge, by its nomenclator (Dr. Krefft, of Melbourne, Aus- 

 tralia), provoked earnest investigation of its structure, and to Dr. Giinther 

 (see p. xi), we are indebted for an elaborate description thereof. The 

 light derived from this examination was reflected upon the allied extinct 

 types, and it was clearly shown that the order, once regarded as so isolated, 

 had been rich in representatives in the distant past. 



And for various other additions to our knowledge of these forms, we are 



1 Published in the Archiv (pp. 138-141) as an appendix (Nachtrag) to his memoir 

 on the Ganoids. 



2 Published originally in the Archiv fur Naturgeschichte (9 Jahrg., b. I, p. 292- 

 330), where it appeared with the title " Beitrage zur Kenntniss der naturlichen 

 Familien der Fische," but considerably modified, and especially by the exclusion of 

 the Dipnoan and Ganoid fishes from the series. See, also, pp. 155, 158 (Gobo'idei vice 

 Cyclopodi),+ 159-160 (Scales) 175-178 (Anacanthini),182 (degrading Goniodontes), 

 18G (Aplochiton, Microstoma), 187 (Galaxise), 188 (Esoces), 190-192 (Clupeidse), 

 192 (-f- Heteropygii), 193-194 (Apodes). 



8 HPXLEY (Thomas Henry). Preliminary Essay npon the Systematic Arrangement 

 of the Fishes of the Devonian Epoch, .... < Memoirs of the Geological 

 Survey of the United Kingdom. Figures and Descriptions illustrative of British, 

 organic remains. Decade x., 1861, pp. 1-40. 



I 



