-38 Fossil Fishes. 



" From this state of things, and from the manner in which I have 

 been obhged to study living fishes, that I might compare them with 

 fossil ones, a great advantage has resulted in the complete indepen- 

 dence I was required to maintain concerning all the former reputed 

 alliances of different fishes ; because the great number of new species 

 which have been discovered since the commencement of the present 

 century, for the most part represented in the Rcgne Animal of Cu- 

 vier, and which it was necessary to insert in the groups of the natu- 

 ral families of this class, has caused all the alliances proposed by the 

 older Ichthyologists entirely to disappear. In afresh reviewing their 

 characters, I have been led to adopt a classification which differs 

 considerably from any arrangement which has hitherto been propo- 

 sed, and which is founded upon important considerations which have 

 hitherto been neglected. 



"It admits of no doubt, that one of the distinctive characters of 

 the class of fishes, consists in the skin being possessed of scales of a 

 peculiar form and structure. This covering, which protects the an- 

 imal externally, has, according to all the observations 1 have made 

 up to the present moment, the most direct relation to its interior or- 

 ganization, and to the external circumstances in which the animal is 

 placed. So that, in this point of view, the scales acquire a primary 

 importance, and may be regarded as a superficial reflection of all that 

 passes within and around the fish. Accordingly, upon attentively 

 examining them, I have found that fishes may be arranged in an or- 

 der much more natural than any hitherto proposed, by allowing our- 

 selves to be regulated by the structure of the scales. Acting on this 

 principle, I have established four orders, which present some resem- 

 blance to the great divisions of Artedi and Cuvier, but one of which, 

 hitherto almost wholly unknown, is nearly exclusively formed of ge- 

 nera, the species of which are found solely in the older strata of the 

 crust of the globe. These four divisions are — the Placo'ides, which 

 includes all the cartilaginous fishes of Cuvier, with the exception of 

 the Sturgeons ; the Gano'ides, which comprehends more than fifty- 

 extinct genera, and with which it is necessary to ally the Plectogna- 

 thes, the Syngnathes, and the Acipenser ; the Cteno'ides, which are 

 the Acanthopteryglens of Cuvier and Artedi, to the exclusion, how- 

 ever, of all those which have smooth scales, and including with them 

 the Pleuronectes ; and, lastly, the Cycloides, which are principally 

 the Malacopteryglens, but which likewise comprehend all the fami- 

 lies which are excluded from the Acanthopteryglens of Cuvier, and 



