In Silurian and Devonian Epochs 133 



3000 miles removed, and it is from Australia that primitive 

 Carboniferous fishes have been obtained. The genera how- 

 ever of these are the same as those recorded from India, 

 Russia, Scotland and N. E. America, and all are of fresh- 

 water habitat. Six also of the above-named genera were 

 first found in North Europe, so that a possible generic 

 distribution, almost from pole to pole, during Old Red and 

 Carboniferous times, seems to be indicated, and this by 

 way of Eastern Australia. With the above two papers 

 before us the conclusion then seems sound, that from near 

 the North Pole to near the South Pole an extensive area 

 of land once existed, the lakes, rivers, and flood-plains of 

 which harbored related genera and even allied species of 

 fish. These were so numerous that abundant remains of 

 them are now being laid bare from widely apart centres. 



The map that forms Fig. 15 (p. 136) suggests possible 

 land areas during Upper Old Red and Carboniferous times. 

 The land areas however may have been greater. 



As to the food and mode of feeding of the Silurian and 

 Old Red fishes, all evidence indicates that the Agnatha were 

 devoid of teeth, and were "bottom-feeders." Again the 

 primitive dipneustians like Coccosteus, Macropetalichthys, 

 and Dipterus were wholly devoid of ordinary cutting teeth, 

 and only had broad tubercled crushing plates in the lower 

 palate. So these resembled, but were more primitive than, 

 the similar plates of such a living dipnoan as Neoceratodus 

 of Australia. Now we know that the three living dipnoan 

 genera {Neoceratodus^ Lepidosiren, Protopteriis) feed 

 largely on aquatic vegetation, but also in part on small 

 freshwater animals. The frequent accumulation of crushed 

 vegetable remains, or of teeming masses of phyllopod crust- 

 aceans, alongside these primitive fishes, would indicate that 

 they, like their existing dipnoan descendants, were largely 

 herbivorous, possibly to a less degree dependent on small 

 and soft animal prey. 



The appearance of chondrostean types like Cheirolepis, 

 and of crossopterygian types like Osteolepis and Megal- 

 ichthys with dentarian teeth of small to moderate size, sug- 

 gest the catching of small prey, as is true of their nearest 

 descendants of to-day. 



