22 FISHES. 



field of research by his study of the infinite variety of fossil 

 forms. In his principal work, " Eecherches sur les Poissons 

 fossiles," (Neiichatel, 1833-43, 4to, atlas in fol.), he placed 

 them before the world arranged in a methodical manner, with 

 excellent descriptions and illustrations. His power of discern- 

 ment and penetration in determining even the most frag- 

 mentary remains is truly astonishing ; and if his order of 

 Ganoids is an assemblage of forms very different from that 

 as it is circumscribed now, he was at any rate the first who 

 recognised that such an order of fishes exists. 



The discoverer of the Ganoidei was succeeded by their 

 J. Miiller. explorer, Johannes Mullee (born 1801, died 1858). In his 

 classical memoir " Ueber den Bau und die Grenzen der 

 Ganoiden" (Berlin, 1846 ; 4to), he showed that the Ganoids 

 differed from all the other osseous fishes, and agreed with the 

 Plagiostomes, in the structure of their heart. By this primary 

 character, all heterogeneous elements, as Siluroids, Osteoglos- 

 dda\ etc., were eliminated from the order as understood by 

 Agassiz. On the other hand, he did not recognise the affinity 

 of Lepidosircn to the Ganoids, but established for it a distinct 

 sub-class. Dipnoi, wliich he placed at the opposite end of the 

 system. By his researches into the anatomy of the Lam- 

 preys and Amphioxus, their typical distinctness from other 

 cartilaginous fishes was proved ; tl^ey became the types of 

 two other sub-classes, Cydostomi and Lcptocardii. 



Miiller proposed several other not unimportant modifica- 

 tions of the Cuvierian system ; and although all cannot be 

 maintained as the most natural arrangements, yet liis re- 

 searches have given us a much more complete knowledge of 

 . the organisation of the Teleosteous fishes, and later en- 

 quiries have shown that, on the whole, the combinations pro- 

 posed by him require only some further modification and 

 another definition to render them perfectly natural. 



