16 



PEOCEEDINGS OP THE NATIONAL MUSEUM 



VOL. 7a 



each of them. Kraepelin (1905) gives the number of genera and 

 species for the zoogeographical regions as follows : 



Qenera 



Species 



Ethiopian.. 

 Palaearctic. 



Oriental 



Australian. . 

 Nearctic — 

 Neotropical 



Four genera are now known to occur in the United States, 

 are keyed out as follows : 



KEY TO THE GBNBHA OP BUTHIDAB OCCURRING IN THE UNITM) STATES 



They 



A\ First tarsal segment of legs III and IV with a distal spur Uroplectes Peters. 



A'. First tarsal segment of leg IV without distal spur, 



B\ Oblique rows of teeth on fingers of chelae flanked with supernumerary- 

 rows of teeth Centruroides Marx, 



B'. Fingers of chelae without flanking supernumerary rows of teeth. 

 C\ Most of oblique rows of teeth on fingers of chelae overlapping. 



Tityus Koch. 

 C^ Rows of teeth on fingers of chelae not overlapping. 



Isoraetrus Hemprich and Ehrenberg. 



Genus UROPLECTES Peters 



Uroplectes differs from our other genera of Buthidae in having 

 a distal spur on the first tarsal segment of legs III and IV. It is a 

 genus that belongs to the Old World, our species apparently being 

 an introduction. 



UROPLECTES MEXICANIJS Comstocks 



MEXICAN UROPLECTES 



Under this name Comstock (1912) describes a species as follows: 

 " This is a pale species. There is no spine under the sting; the teeth 

 on the finger of the palpus are in many oblique rows, with stouter 

 teeth at the end of each and to one side; there are from 30 to 35 

 teeth in the combs ; and the keels on the under side of the last caudal 

 segment are very strongly toothed." 



He writes that the species has been found in Texas and California. 

 Kraepelin (1905) is of the opinion that this scorpion probably was 

 introduced from the Old World. Banks (1910) does not include it 

 in his list of California scorpions. There are no specimens of Ameri- 

 can Uroplectes in the National Museum collection. 



* Comstock's 1912 description is tlie first for this species. 

 Banks's manuscript name Uroplectes mexicamis. 



He appears to have used 



