KEY TO THE FAMILIES AND GENERA OF SCORPIONS 



1. With two eyes on each side of the cephalothorax (besides the ones near 



the mid'hne) ; Cal. 



Chactidae, Broteas Koch 

 With three or more eyes on each side of the cephalothorax 2. 



2. Sternum triangular — Buthidae 3. 

 Sides of sternum parallel 6. 



3. With oblique rows of tiny, spiny projections on the claws of the pedi' 



palps, with a row of smaller spines on either side and parallel to them; 

 southern U. S. 



Centrums Ehrenberg 

 With oblique rows of tiny, spiny projections on the claws of the pedi' 

 palps, unaccompanied by parallel rows of smaller spines 4. 



4. No spine under sting; third and fourth legs with a spur at the distal end 



of the first tarsal segment; Texas, Cal. 

 Uroplectes Peters 

 With a spine under the sting; fourth legs without a spur at the distal 

 end of the first tarsal segment 5. 



5. With the rows of spines overlapping; Fla. 



T-ityus Koch 

 With the rows of spines almost end to end; Fla. to Cal. 

 Isometrus Hemprich & Ehrenberg 



6. With one spur on the outside of the last segment of the last leg 



Scorpionidae 7. 



With one or two spurs on each side of the last segment of the last leg 



Vejovidae 8. 



7. With a knob below the sting; southern U. S. 



D}plocentrus Peters 

 No knob below the sting; Fla. 



Opisthacanthus Peters 



8. Movable claw of chelicerae (first pair of mouth appendages) without 



teeth; southern states 

 Vejovis Koch 

 Movable claw of chelicerae with one or more teeth below 9. 



9. Middle area of combs (area between the "teeth" and the "back" of the 



combs, a pair of which are situated on the front of the lower side of 

 the abdomen) composed of eight pieces each; southwestern states 

 Hadrurus Thorcll 

 Middle area of combs composed of six or less pieces 10. 



10. With three or less teeth on the movable claw of the chelicera; southwest' 

 ern states 



Anuroctonus Pocock 

 With four or more teeth on the movable claw of the chelicera; West 

 Coast 



Uroctonus Thorell 



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