ANATOMY AND GENERIC CHARACTERS OE SCORPIONS. 379 



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



Class ARACHNIDA. 



Grade A. Delobranchia (Limulus and Eurypterines). 

 Grade B. Embolobranchia. 



Order 1. Scorpionidea. 



Order 2. Pedipalpi. 



Order 3. Araneidea. 



Order SCORPIONIDEA. 

 Fam. unic. SCORPIONIDiE. 

 Subfamily I. Scorpionini. 

 Sternum (metasternite) pentagonal, quadrate, or compressed autero-posteriorly, and 

 divided into two narrow triangular pieces, right and left (=chilaria of Limulus). 



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. Lamella? of the pectens very few ; lateral eyes two ; spiracles oval ; tail slender. 

 Type Euscorpius italicus : South Europe. (PI. LXXXII. fig. 3.) 



Subgenus Buthus (=IIeterometrus, Ehr.). 

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

 tail slender. 



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



Subgenus Brotheas. 

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



thick. 



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



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



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



