302 



ARACHNIDA SCORPIONIDEA 



CHAP. 



eyes of Limulus. The arrangement of various slight longi- 

 tudinal ridges on the dorsal surface of the carapace is of systematic 

 importance. On the ventral surface, just in front of the genital 



hand 



, Pedipalp 

 Lateral ei/es 

 Afecfian eyes 



Protoma 



A/esosoma 



sternum 



ff en it at 

 'operculum 



-Pectines 



^stigmata 



Metasomo 



aculeus. }/ 'vesicle 

 FIG. 169. Buthus occitanus. A, Dorsal view; B, ventral view. (After Kraepelin. ) 



operculum, is a sternum, never large, and sometimes barely 

 visible. Its shape and size constitute one of the principal 

 family characteristics. 



Mesosoma. The dorsal plates or terga are distinct, and are 

 connected by soft chitin with their corresponding sterna. 



Beneath the second abdominal segments are borne the 

 "pectines" or comb - like organs. In their structure four 

 portions are distinguishable, an anterior lamella or shaft attach- 

 ing them to the body, a middle lamella, the teeth, and the 

 fulcra, a series of small chitinous pieces intercalated between the 

 bases of the movable teeth. 



