Palaeozoic Arachnida of North America. 37 



as a small variety of E. carhonarius if there were more gradations be- 

 tween the two. As it is, both types being probably gravid females, 

 I thought it wiser to regard E. typicus as specifically distinct from 

 E. carhonarius. It may be objected that since the additional charac- 

 ters of the genus are derived from new species, th& genus Anthraco- 

 scorpio should have precedence. But the characters of the latter 

 genus are also based on a defective specimen and were supplemented 

 later when new species were found. Besides, if we were to accept 

 Pocock's definition of Anthracoscorpio, then Eoscorpius typicus would 

 certainly have to be placed under that genus and with it E. carhona- 

 rius, on account of its extreme similarity. The name Eoscorpius 

 has priority and should therefore not be changed. 



The Palaeozoic scorpions of the genus Eoscorpius resemble most 

 some of the recent Vejovis. 



Key to North American Species of Eoscorpius. 



1. Cephalothorax as long as wide, or longer than wide. Ej'es 



removed from anterior edge 2 



+ cephalothorax wider than long. Eyes closer to anterior edge 3 



2. Sixth abdominal tergite wider than ist. Size about 90 mm. 



E. carhonarius 

 + first abdominal tergite wider than 6 th. Size from 45 to 65 mm. 



E. typicus 



3. Abdominal tergites smooth. 



E. danielsi 

 + abdominal tergites with a transverse row of punctuated 

 depressions along their posterior border. 



E. granulosus 



Eoscorpius carhonarius jMeek and Worthen. 

 Plate II, figure 6. 



E. carhonarius Meek and Worthen, Amer. Jour. Sci. & Arts (2), 

 Vol. XLV, 1868, p. 25. Geol. Surv. 111., Vol. Ill, 1868, p. 560 

 with fig. 



The obverse of the type specimen in the Museum of the University 

 of Chicago, the reverse in the University of Illinois collection. 



Careful examination of both halves of this important fossil con- 

 vinced me that the description of Meek and Worthen is quite correct 

 and that nothing of importance could be added to it. I therefore 

 quote it here with such abbreviations as seem to be advisable and 

 with the substitution of metric measurements for inches. 



