578 



ARTHROPODA. 



also known, and these ancient types do not appear to have differed 

 from the living representatives of the group except in comparatively 

 non-essential characters. 



The genus Palceophonus (fig. 433) has been detected in the Silu- 

 rian strata of Gotland and of Scotland, and comprises Scorpions 

 which differ from all existing types in the fact that the walking-legs 

 gradually taper to their ends, which terminate in points or simple 

 claws. The maxillary palpi form strong nipping-claws, and the 

 median eye-tubercles are placed not far from the anterior margin of 

 the cephalothorax. The genus Proscorpins occurs in the Silurian 

 deposits of North America, and differs from the preceding in the 



Fig. 433. — Ventral aspect of a species of 

 Palcpophoiius, from the Silurian rocks of Les- 

 mahagow, Lanarkshire. Enlarged nearly 

 twice. (After Benjamin N. Peach.) 



Fig. 434. — A specimen of Eoscoi-pius carbon- 

 arhcs, from the Carboniferous rocks of Illinois, 

 of the natural size. (After Meek and Worthen.) 



fact that the legs are long, with blunt terminal joints ending in two 

 claws. The median dorsal eye-tubercles are placed on the anterior 

 margin of the cephalothorax, and the lateral eyes are on ridges, as 

 in the living Scorpions. The genus Eoscorpius (fig. 434) is confined 

 to the Carboniferous rocks, and species have been detected in the 

 Coal-measures of both Europe and North America. Mazonia is 

 probably identical with Eoscorpius. The genus is nearly related to 

 Proscorpius, from which it differs in having the median dorsal eye- 

 tubercles of smaller size, and not placed close to the anterior margin 

 of the cephalothorax. The Coal-measures of Europe and North 

 America have also yielded the remains of Scorpions on which the 

 genus Cydophthalmus — including the first fossil forms known to 



