AET. 9 SCOEPIOISrS OF WESTEEI^ UNITED STATES EWING 17 



Genus CENTRUROIDES Marx 



In Centruroides the first tarsal segment of leg IV is without a 

 distal spur; the teeth of the fingers are arranged in oblique rows 

 with supernumerary rows on each side. This genus is exclusively 

 American, but in this continent has a wide range, being found from 

 Central United States to Chile. Many species are included in it. 

 A key is here given to those of the western part of our country. 



KEY TO THE CENTEDKOIDES OF WESTEBN UNITED STATES 



A\ Length over 8 cm. ; body unstriped. Large dark species. 



B\ Fingers of hand furnished with nine middle rows of teeth, exclusive of 



short apical row _~ C. nigrescens Pocock. 



B*. Fingers of hand with only eight middle rows of teeth, exclusive of short 



apical row C. margaritatus (Gervais). 



A*. Length less than 7 cm. Reddish brown or striped species. 



B'. Sting without ventral spine or tubercle near base ; fingers one and a half 



times as long as hand C. exilicaudata (Wood). 



B^ Sting with a ventral spine or tubercle. 



C\ Abdomen with two more or less interrupted longitudinal stripes 

 above ; sting with a spinelike tubercle below. 

 D\ Black stripes irregular but never appearing as a row of dots. 



Eastern species C. vittatus (Say). 



D^ Black stripes partly or entirely interrupted at each body seg- 

 ment so as to appear as a row of spots. Found in Cali- 

 fornia C. calif ornicus (Girard). 



C^. Abdomen without longitudinal stripes; sting with a vestigial tubercle 

 below ; dorsal surface of abdomen very rough. 



C. sculpturatus, new species. 



CENTRUROIDES NIGRESCENS (Pocock) 

 BLACK SCORPION 



G. nigrescens is a large, long, black scorpion. The color varies 

 from a very dark chestnut brown to a jet black. The appendages 

 are slender, the fingers being about one and a half times as long as 

 the hand. The postabdomen is much longer than the abdomen. The 

 sting is very long and curved with a sharp subaculear tubercle. A 

 large National Museum specimen measures 10 cm. in length. 



Pocock (1902) reports this species from Xautipa and Amula in 

 Guerrero, Orizaba, Mexico. Borelli (1909) does not mention it in 

 his list. Banks (1910) does not give it in his list of California 

 scorpions. In the National Museum collection there are two speci- 

 mens from Eagle Pass, Tex., and one from San Antonio, Tex. 

 H. B. Parks, apiculturist at the state apicultural research labora- 

 tory, a few miles south of San Antonio, Tex., told the writer that 

 he is familiar with a large, black scorpion the description of which 

 fits this species. WTiile collecting scorpions at San Antonio the 

 writer did not see any examples of the species. 



