2o6 Evolution and Distribution of Fishes 



of Coelacanthiis, Coccolepis australis, Aetheolepis mirahilis, 

 Archaeomaene tenuis, and A. rohustus, Leptolepis talbra- 

 garensis, L. lowii, and L. gregarius. The association of 

 insects and plants, as well as the complete absence of any 

 marine organisms, stamp the deposit and the fishes as fresh- 

 water. But the occurrence of fossilized shoals of the first- 

 named Leptolepis, at once recalls Walther's description of 

 L. sprattiformis in the Solenhofen Slates. Again in speak- 

 ing of Coccolepis Woodward says : "The genus thus de- 

 fined is represented by small species in the lithographic stone 

 (Lower Kimmeridgean) of Bavaria {Coccolepis buck- 

 landii), and in the Purbeck beds and Lower Lias of 

 England. It is therefore of much interest to find a large 

 fish in the Hawkesbury-Wianamatta series of Talbragar, 

 exhibiting characters so similar as not to be more than 

 specifically distinguishable." 



Aphnelepis, in its near relation to Semionotus and 

 Aetheolepis,, and as a specialized ally of the Liassic Dape- 

 dius, serves with the above to link the Australian and 

 European fish-fauna in close manner. As to the preserva- 

 tion of these, and as shedding some light on the Solenhofen 

 shales, the author says : "The fishes are crowded together 

 as if suddenly destroyed and very few of them have become 

 disintegrated before fossilization. A glance at the ac- 

 companying plates will show how beautifully even the most 

 delicate bones and fin-rays are usually preserved." In des- 

 cribing and figuring the scales alike of Aetheolepis and 

 Archaeomaene he also demonstrates the graded continuity 

 shown (Fig. 54, p. 330) from a ganoid to a perfect 

 cycloid type. If to this we add the close anatomical struc- 

 ture of these and of related genera to primitive and de- 

 rived teleosteans, that were, like these, dwellers in fresh- 

 water, a clear way is opened for understanding how and 

 where primitive teleosteans first evolved, and why it is that 

 a large proportion of these are still freshwater. It explains 

 also how derivative types, during subsequent Cretaceous 

 and Tertiary times, gradually passed into and stocked the 

 seas and oceans with what are now the dominant fishes, both 

 as regards genera and individuals. 



