FISHES. 123 



donts " at all. Other views have been advanced by other 

 authorities ; hut without entering into these further, it will 

 he sufficient to note that Professor Newberry, one of our 

 most distinguished authorities upon fossil fishes, after an 

 examination of a large number of these bodies from the 

 Carboniferous rocks of North America, has declared himself 

 as inclined to the view that they are really the minute 

 teeth of Cyclostomatous fishes allied to the living Lampreys 

 and Hag-fishes. As these Fishes possess a cartilaginous 

 skeleton and a scaleless skin, and have thus no other 

 structures than their teeth which could possibly be pre- 

 served in a fossil state, there is no a ^priori improbability 

 in this -^dew. Indeed, the fact that fishes of as high rank 

 as the Ganoidei and Masmohranchii existed in the Upper 

 Silurian, would render it quite probable that the much lower 

 order of the IlarsijMhranchii had been developed in tunes 

 as early as the Lower Silurian or Cambrian. 



In the undecided state of this question, we cannot posi- 

 tively assert anything as to the past distribution of the 

 Marsipdbranchii. If the "Conodonts" should prove to be really 

 the teeth of fishes like the Lampreys and Hags, then this 

 order is the most ancient of all the groups of the Fishes, and 

 must have been largely represented throughout the Palaeo- 

 zoic period. On this point, at present, we can only suspend 

 our judgment. The still lower order of the Pharyngo- 

 Iranchii, including only the living Lancelet, may be safely 

 dismissed from our consideration, as no structures capable 

 of preservation in the fossil state are developed in this 

 order, and we can therefore never know anything as to its 

 past history. There remain, therefore, for consideration 

 only the orders of the Teleostei (Bony fishes), Ganoidei 

 (Ganoids), Elasmohranchii (Sharks and Kays), and Dipnoi 

 (Mud-fishes). 



