ARACHNIUA SCORPIONIDEA 



eyes of Limulus. The aiTaugement 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 



,^itiffmaCa 



>Meeaso/no 



Fig. 169. — Buthus vccitaiius. A, Dorsal view ; B, ventral view. (After Kiaepelin.) 



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. 



