Hv. PRESIDENTS ADDRESS. 



affinities to the Chinuziida:, had better be retained as a distinct 

 Sub-Order of which Lepidosiren, Protopterus, and Ceratodus are 

 the only living representatives. Lepidosiren paradoxa is found 

 living in the system of the Amazons. Protopterus annectens is 

 limited to the rivers of tropical Africa, and is the only known 

 species of this genus. Ceratodus is one of the few instances 

 where a genus established on the evidence only of fossil 

 specimens has been afterwards found living. The teeth, which 

 were the only imperishable parts of this cartilaginous fish, had 

 long been known ; it was not, however, until the year 1870, that 

 a living specimen was brought from Queensland, and identified 

 as related to the fossil teeth of Ceratodus, from the Rhaetic Beds 

 .of Aust-cliff, near Bristol. The teeth are found in widely distant 

 regions of the world, in the Trias, in the Jurassic Beds of the 

 Colorado, South America, and in the Stonesfield Slates of these 

 Islands. The peculiarity of the living Ceratodus is its being 

 able to exist for a considerable time buried in the mud during 

 the dry rainless seasons. 



Dipnoid Fish have a persistent notochord, which passes 

 uninterruptedly into the cartilaginous base of the skull, the 

 posterior part is more or less ossified. The fore-fins differ 

 from the pectoral fins of the Ganoids, they are flexible in 

 every direction, and in every part. The jointed axis of this 

 fin is retained in the Lepidosiren, which is destitute of rays ; 

 on the other hand that of the Protopterus is furnished with 

 fin-rays. 



Ganoidei occupy an intermediate position between the 

 Selachii, Dipnoi, and Teleostei, having characters common with 

 each. They appeared as early as the Silurian Age, and were 

 contemporaneous with the Sharks and Rays, forming a large 

 proportion of Fish-life at that period. This Order is difficult 

 of definition owing to extreme diversities of the forms. The 

 body is either naked, or covered with a shagreen skin, with 

 large detached bony scales, like the Sturgeon, or with the true 

 ganoid scales. The vertebral column is either cartilaginous 

 or fully ossified ; the tail diphycercal, or heterocercal ; the 



