OF ARTS AND SCIENCES. 21 



when there is more than one intermediate series. (2d.) Besides these, 

 there is a single marginal row of processes, the teeth of the comb, 

 which are as numerous as the scales of the posterior row to which 

 they correspond. 



To judge from Mr. Peach's figures and descriptions, the anterior 

 row, which in modern scorpions forms the backbone of the comb, and 

 is mostly made up of a single plate very broad at base, is just as weak 

 in structure as the intermediate lamellae, which are also excessively 

 reduced and multiplied ; or perhaps the anterior row is entirely want- 

 ing, and its place occupied by a vegetative development of the " inter- 

 mediate " series, a view which might be re-enforced from what is known 

 of Meek and Wortheu's species. The teeth also in one of Mr. Peach's 

 examples are represented apically by a " double row of leaflets, which 

 overlap in an imbricating manner like tiles." On the other hand, the 

 figure which Fritsch has given us of Corda's Bohemian species re- 

 sembles modern types much more closely except in the entire absence 

 of the intermediate series, throwing some doubt upon the constancy of 

 the characters apparently derivable from the other sources. 



The differences which exist should certainly not be ignored, and it 

 may lead to an earlier decision of the question whether distinctions 

 any broader than mere generic ones may separate the earlier from the 

 modern forms, if we jDlace these paleozoic forms in a distinct family, 

 and endeavor to define their characteristics. This we propose doing 

 under the following provisional characters. 



EOSCORPIONIDiE nov. fam. 



A pair of sternal plates interposed visibly between the coxae of the 

 second pair of legs. Posterior sternal plates, corresponding to the 

 " sternum " of living scorpions, quadrate, large, of about equal length 

 and breadth. Both intermediate and dorsal lamellae of the combs very 

 numerous, rounded and small, subequal, and not larger than the fulcra, 

 arranged in many rows, the teeth numerous and forming a single row 

 toward the base of the comb, but a double imbricated row apically. 

 Hands slender. Mesial eyes very large and elevated. Five lateral 

 eyes of equal size on each side, forming a single continuous semicircle 

 around and behind the mesial eyes. 



EoscoRPiDS Meek and Worthen. 



Eoscorpius carhonarius Meek and Worthen, Geol. 111., iii. 560-562, 

 fig., 1868. Bufhus? carhonarius Ibid., Amer. Journ. Sc. Arts, (2,) 

 xlvi. 22-24, 1868. Mazon Creek, 111. 



