ARACHNIDA. SCORPIONIDA 



353 



Although this Order is of great antiquity, it has 

 but few fossil representatives. 

 Palceophonus (fig. 151) occurs in 

 the Silurian rocks of Gothland 

 and Lanarkshire ; Proscorpius in 

 the Silurian of North America. 

 Eoscorpius is found in the Car- 

 boniferous of Scotland, the Mid- 

 lands, and North America. Im- 

 perfect specimens of scorpions 

 have been obtained from the 

 Trias of Warwickshire. One 

 form {Tityus) is known from the 

 Oligocene beds. 



Eoscorpius does not differ 

 in any important respect from 

 living scorpions, and appears to 

 have been quite as highly or- 

 ganised. Palceophonus (fig. 151), 

 however, is rather more primi- 

 tive in some of its characters ; 



the walking legs consist of nearly equal-sized joints and 

 seem to be without claws; the basal joints of all these 

 legs could serve to some extent as jaws and in this respect 

 resemble the walking legs of Limulus and still more those 

 of the Eurypterida. Palceophonus, unlike later scorpions, 

 seems to have been aquatic, since it is found associated 

 with marine fossils, and moreover, stigmata appear to 

 have been absent — probably therefore it breathed by 

 means of branchial lamellae instead of lung-books. 



Fig. 151. Palceophonus cale- 

 donicus from the Upper 

 Silurian of Lesmahago, 

 Lanarkshire. Restoration 

 of ventral surface by R. I. 

 Pocock. x 1£. 



W. P. 



23 



