Ixiv. PRESIDENT'S ADDRESS. 



nerves ; and is much larger than the organs of sensation and 

 movement of the same animals. 



Of all the Vertebrates, Fishes possess conditions the most 

 favourable for preservation in a fossil state. No other class has 

 furnished so complete and so numerous a list of remains, owing 

 to their having been covered by the fine sand or mud in which 

 they were deposited. The number of species of the present day 

 far outnumber those of past geological ages. During the 

 Tertiary Age some localities appear to have had a fish-fauna 

 analogous to the one now existing, both in numbers and variety. 

 The earliest remains of fish occur in the Upper Silurian Beds 

 of Ludlow. The most productive beds of this age are the 

 Provinces of the Russian Baltic. Compared with the Old Red 

 Sandstone, the other members of the Devonians of Europe are 

 very poor in fish-remains. The American beds of that period are 

 productive, but on the contrary they differ in the entire absence 

 of Pteraspidip.y Cephalaspfdce, and Acanthodidce. The fauna of the 

 Old Red Sandstone period appears to have been littoral, confined 

 to shallow-water, and probably brackish. The Pteraspidae and 

 Placodermi did not survive the advent of the Carboniferous Age, 

 whilst the Selachii {Sharks and Rays] which had hitherto been 

 rare began to take a prominent part, becoming less rare in the 

 succeeding Permian Age. The sudden interruption in the 

 development of animal life towards the end of the Palaeozoic 

 Age was equally shared by the Fish-fauna. Among the Dipnoi 

 the Ceratodus is conspicuous in the Trias and Jurassic Beds. 

 The appearance of the Teleostei in the Permian is doubtful. There 

 are, however, a few genera of that age, which, notwithstanding the 

 incomplete ossification of the vertebral column, bear some resem- 

 blance to them. The Order Lepidosteidae is characteristic of the 

 Fish-fauna of the Trias, and continues through the Jurassic to 

 the Cretaceous. Agassiz and Egerton assign 76 species to the 

 Lias out of 152 known Teleostei. The Lepidosiren, Protopterus, 

 Ceratodus, and Sturgeon are of some interest, as they recal to 

 mind the palaeozoic ancestry. The majority of the Upper 

 Jurassic fish belong to the families Lepidosteidse, Amiidse, and 





