400 ARACHNID A, MYRIAPODA, AND INSECT A. 



As regards their distribution in time, the Scorpions com- 

 mence in the Carboniferous period, where they are represented 

 by the genera Eoscorpius and Cyclophtlialmus. The most cele- 

 brated fossil Scorpion is the CyclophtJialmus senior (fig. 251) 

 of the Bohemian Coal-measures. This remarkable form re- 

 sembles the living Androctonus in having twelve eyes, but 

 these are disposed in a circle, whereas in the latter there are 

 six eyes on each side of the head. The Eoscorpius carbona- 

 rius, of the Coal-measures of Illinois, is also a true Scorpion, 

 and is most nearly related to the recent genus or sub-genus 



Fig. 251. Cyclophthalmus senior. A fossil Scorpion from the Coal-measures of Bohemia. 



Buthus, from which it does not seem to be separated by any 

 characters of great importance. 



Besides the typical Scorpions, the order Pedipalpi likewise 

 contains various forms like the living Phrynus and Thely- 

 plwnus, in which the maxillary palpi are not chelate ; and 

 we appear to have ancient representatives of these in the 

 Eophrynus and Arthrolycosa of the Carboniferous rocks. In 

 the former of these (fig. 252, A) the dorsal surface of the 

 abdomen is tuberculated, and the ventral surface exhibits six 



