LIFE 



467 



in 



: 



Intercontinental migration seems to have come to an end by the 

 ose of the period. 



Insects. Hundreds of species of insects have been identified 

 nun the Coal Measures. They were, for the most part, rather 

 primitive types. Orthopters (cockroaches, i, Fig. 402, locusts, 

 crickets, etc.) were greatly in the lead, followed by neuropters (repre- 

 nted by ancestral mayflies). These two orders include about 90 

 r cent of the known insects. Hemipters (bugs), which had ap- 

 ared earlier, and possibly coleopters (beetles) were present, but no 

 fossils of bees, butterflies, or moths have been found, and there is 

 little probability that they existed, since flowering plants, on which 

 they depend, had not yet appeared. There is no record of flies. 

 The evolution of insects was therefore one-sided. Curious forms 

 were developed within the orders which lived, and remarkable sizes 

 were attained, spreads of wing of a foot or more being reported. 



Spiders and myriapods (Fig. 402) were plentiful, and several 

 species of land snails (d and e) have 

 een identified. The amount of ear- 

 on dioxide in the atmosphere could 

 not have exceeded that compatible 

 wjth this varied assemblage of air- 

 breathing life. 



Fresh-water Life 



Besides fresh-water plants, the 

 life of land waters appears to have 

 consisted of fishes, mollusks, crus- 

 taceans, and doubtless of many other 

 forms. Aside from the development 

 the fresh-water fish and amphibia, 

 jrhaps the most suggestive feature 

 fas the association of the arthropods 

 fiih other forms of life. Eurypterids 

 (Fig. 403) were still in existence, and 

 u-ir relics are so intimately associ- 

 ited with ferns, calamites, insects, 

 )iders, and scorpions as to leave no 

 ;asonable doubt that they were 

 resh-water forms. There were also crustaceans resembling cray- 

 ish, and others of shrimp-like appearance. 



Fig. 403. Natural association 

 of Euryptcrus mansficldi with 

 ferns and calamites. (From Dana 

 after Hall.) 



