424 THE CARBONIFEROUS PERIOD 



extinct division, Palceocrinoidea, none of which, passed over into 

 the Mesozoic era. Of the long list of Crinoids found in the rocks 

 of this system may be mentioned : Actinocrinus, Platycrinus, 

 Rhodocrinus, Onychocrinus (V, 6), ALsiocriniis (VI, 2). 



The Echinoids, or sea-urchins, are still far less abundant than 

 the Crinoids, but they are much more numerous and varied, and 

 of larger size than they had been before. The Carboniferous sea- 

 urchins are, like those of the preceding periods, members of the 

 ancient and now extinct subclass, Palceoechinoidea, and the com- 

 monest genera are Melonites (V, 7), Oligoporus, and Archceo- 

 cidaris. In addition to these should be noted the beginning of 

 the modern subclass, Euechinoidea, as the still existing genus 

 Cidaris is reported from the Carboniferous. 



The first known Holothnroidea, or Sea-cucumbers, date from 

 this period. 



Arthropoda. — The Trilobites have become rare and are soon 

 to die out altogether ; most of the species belong to the peculiarly 

 Carboniferous genera Phillipsia (V, 13) and Griffithides, but the 

 Devonian Proetus still persists. The Eurypterids continue, even 

 into the coal measures, but they cannot compare in size or num- 

 bers with the great Devonian forms. Phyllopods and Ostracods 

 are abundant, and in the coal measures are found members of the 

 highest crustacean group, the Decapods, of which Anthracopalai- 

 mon is the best known genus of the time. 



Myriapods and Scorpions are much commoner than in the De- 

 vonian, and the first of the true Spiders are found here. Insects 

 likewise show a great increase in numbers, though the Orthopters 

 and Neuropters are still the principal orders represented. Many 

 of the Carboniferous insects are remarkable for their great size, 

 some of them measuring nearly a foot across the extended wings. 

 The character of the vegetation has a very direct influence upon 

 insect life, and the monotonous, flowerless Carboniferous forests 

 could not have supported butterflies, bees, wasps, ants, or flies. 

 No insects of these groups have been found in the rocks of that 

 system, and it is not yet certain whether even beetles were then 

 in existence. 



