§ 32. 



SCALES OF FISHES. 



339 



in almost every quarry, until my researches in the chalk- 

 pits around Lewes brought to light many extraordinary 

 specimens, and showed how such delicate remains could be 

 developed.* Professor Agassiz, by whose genius and labours 

 this department of palaeontology has been most successfully 

 elucidated, has adopted a classification of fishes, founded 

 upon the peculiar structure of the scales — a method of 



Lign. 68.— Scales of the four orders of fishes. 



Fig. 1. Scale of Lepidotus ; a fish of the Ganoid order. 



2. — Roy; Placoid -~ . 



3. — Salmon; Cycloid — 



4. — Beryx ; Ctenoid — . 



great utility to the geologist, since the mutilated state in 

 which the fossil remains of fishes generally occur, often 

 renders futile all attempts to refer them to the orders and 

 genera of other systems of Ichthyology, f 



32. Scales of fishes. — M. Agassiz includes all fishes 



* I believe the Fossils of the South Downs (1822) contained the 

 first published figures of fishes from the English chalk. 



t Recherches sur les Poissons Fossiles, par Louis Agassiz : five vols, 

 folio of coloured figures, and two quarto vols, of letter press. 

 z2 



