AJs^ATOMT AND GENERIC CHARACTERS OF SCORPIONS. 379 



I should therefore propose to systematize the Scorpions as follows : — 

 Class ARACHNIDA. 



Grade A. Delohranchia {Limulus and Eurypterines). 

 Grade B. Embololrancliia. 



Order 1. Scorpionidea. 

 Order 2. Pedipalpi. 

 Order 3. Araneidea. 



Order SCORPIONIDEA. 

 Fam. unic. SCORPIONID.E. 

 Subfamily I. Scorpionini. 



Sternum (raetastemite) pentagonal, quadrate, or compressed antero-posteriorly, and 

 divided into two narrow triangular pieces, right and left ( —ckilaria of Lhnulus). 



Nerves to the region of the first pair of lung-books descending from the prosomatic 

 ganglion-mass. Nerves to the region of the second pair of lung-books supplied by a 

 ganglion lying in the third segment of the mesosoma. 



Ornament of the lamellae of the lung-books punctiform. 



A single row of teeth to each ramus of the chelicera ; rarely one tooth of a second 

 row on the movable ramus. 



Genus 1. Scorpio. 

 Char. Sternum pentagonal or quadrate. 



Subgenus Euscorpius. 

 Char. Lamellae of the pectens very few ; lateral eyes two ; spiracles oval ; tail slender. 

 Type Euscorpitis if aliens : South Europe. (PI. LXXXII. fig. 3.) 



Subgenus Buthus {=IIeterometrus, Ehr.). / 



Char. Lamellae of the pectens more numerous ; lateral eyes three ; spiracles slit-like ; 

 tail slender. 



Type Buthus cyaneus of Ceylon. (PI. LXXXII. fig. 1.) 



Subgenus Brotheas. y' 

 Char. Lamellae of the pectens few ; lateral eyes two or three ; spiracles circular ; tail 



thick. 



Type Brotheas suhnitens; Peru. (PI. LXXX. figs. 2, 4, 5, 7, 8, 9, 10, 11, 12.) 



[I should expect to find the characters of the genera Hemiscorpion and Opisthoph- 



thalmus of sufficient importance to entitle them to subgeneric recognition.] 



