THE SCORPIONS OF CALIFORNIA 



NATHAN BANKS 

 OF THE U. S. DEPARTMENT OK AGRICDLTUKE 



The scorpions are readily known from all other arachnids by the presence 

 of two peculiar characters; the body terminates in a poison sting, and on the 

 venter, near the base of the abdomen is a pair of appendages (Fig. 80, d), each 

 bearing a number of lamellae; these are the pectines, or combs. The palpi 

 are enlarged at tip and chelate, the claw being of three parts ; the hand, or 

 basal portion, and two fingers, one movable, the other fixed. There are three 

 groups of eyes on the anterior part of the cephalothorax, one median of two, 

 and a lateral group at each anterior corner, of two or three eyes. The last 

 five segments of the body are much narrower than the others, and form the 

 Cauda, or tail ; the last segment is the "vesicle," and bears the sting. These 

 caudal segments bear ridges, which are called "keels." The legs have no 

 patella between femur and tibia. The mandibles in front consist of a basal 

 [jart, or paturon, (Fig. 80, f), and two curved fingers, one fixed and one 

 movable ; these fingers are usually provided with teeth. Beneath on the venter 

 is a small triangular or pentagonal area between the posterior coxse ; this area 

 is the sternum. 



The poisonous nature of scorpions has been exaggerated by most people; 

 the commoner forms are no more dangerous than a wasp ; one species, Cciitrurns 

 exilicaiida, which occurs in western Mexico and up into the southern part of 

 California, is considered by some to be more poisonous than other species ; 

 however, there is little evidence, as yet, on this matter. 



The species so far known to occur in California are distinguished in the 

 following table : 



1. Between tarsus and metatarsus is a single spur (on anterior side) ; 

 sternum pentagonal ; cephalothorax deeply emarginate in front ; cauda 

 very small ; fingers shorter than hand ; pectines rarely more than 12 in 



number 2 



Between tarsus and metatarsus are a pair of spurs, one in front, one 

 behind 3 



2. No tooth below sting.; hand longer than broad ; pectines not more than 



seven Opisthacoiitlnis Icpliinis. 



A tooth below sting; hand as broad as long; pectines about 10; sur- 

 face of cephalothorax finely granulate Diploccntrus kcyscrlingi. 



3. Sternum long, triangular, with converging sides ; immovable finger of 



mandibles with lower tooth 1 1 



Sternum short, pentagonal ; immovable finger of mandibles without 

 lower tooth ; no tooth below the sting 4 



4. \^'ith but two lateral eyes ; stigmata oval ; with about 7 pectines ; hand 



very broad ; small, short species Brotcocliaclas allciiii. 



With three lateral eyes; stigmata more elongate, usually slit-like 5 



