346 Evolution and Distribution of Fishes 



CHAPTER XII. 



The Evolution of Fishes 

 4. The Soft-Finned Teleostei. 



In beginning our study of the distribution in time 

 and space of the Teleostei, it may be helpful to bear in 

 mind — what all ichthyologists are now agreed on — that 

 the only, and very natural, as well as continuous line of 

 descent of these, is from and through the "ganoids." But 

 as shown in preceding pages the "ganoids" originated in 

 and remained in freshwaters, throughout their entire 

 history, except for a few specialized, and often decadent, 

 offshoots or side lines like the Acipenseridae, Pachycormi- 

 dae, and Pycnodontidae, the first of which is now a rare 

 group and is either freshwater or anadromous in habit. 

 The two latter groups have become wholly extinct, after 

 assuming a marine life. 



It clearly follows therefore that the entire group of 

 Teleostei, started fundamentally, if not directly for each 

 family, as freshwater fishes. This view the writer set forth 

 in 19 1 2 and he published regarding its main details in 19 18, 

 (7:402-405). But had such a viewpoint been secured de- 

 cades ago, many problems would have been rendered easy 

 that have given rise to intricate and prolonged discussions. 

 Not only so, instead of minimizing the wide-spread distribu- 

 tion, richness, and importance of freshwater fishes, through 

 attempts to trace and derive them from a marine ancestry, 

 their high value, from the evolutionary and morphological 

 standpoints would have been recognized, a position that has 

 only in part and slowly been recently accepted from the 

 joint studies of A. S. Woodward, Boulenger and Eigen- 

 mann. 



In viewing existing Teleostei as a whole, it can most cor- 

 rectly and graphically be considered that two divergent lines 

 of descent were early established, and these are indicated 

 by the now somewhat disused or restricted taxonomic terms 

 Malacopterygii and Acanthopterygii, or the soft-rayed and 

 the spiny-rayed Teleosts. But another and equally marked 



