1902.] 



STRIDULATING -ORGAN IN A SCORPION. 



223 



middle line ; but in many of the southern types — e. g., P. plani- 

 manus, P. neglectus, P. villosus — the whole upper surface of the 

 segments tends to become flattened and horizontal both in a 

 longitudinal and transverse direction. A similar granular field 

 is developed between the dorsal keels on the last abdominal 

 terffite. 



Text-fig. 26. 



B 



Stridulating-organ of Parahuthus flavidns. 

 A Lateral view of tail, to show the action of the sting during stridulation. 

 B. Dorsal view of last somite of abdomen and of 1st and 2nd caudal segments, 

 showing the ridges on the median groove of the two segments. 



If the tail of one of these Scorpions be brought into the attitude 

 usually assumed by these animals when striking, and the point of 

 the sting be scraped over the granular field, a very distinct sound 

 is emitted, resembling that produced by drawing the point of a 

 needle over fine sand- paper \ 



There is as yet no direct evidence, based on observation of the 

 living animal, to prove beyond dispute that these granules have 

 the function here assigned to them, but the facts which support 

 the conclusion are the following : — 



(1) The sound can be artificially produced, and is audible to 

 me at a distance of ten yards or more. 



(2) The scorpion itself is capable of performing all the move- 

 ments necessary for its production, 



1 A similar but less complete development of granules, subserving no doubt the 

 same purpose, is observable in two North- African - species of Buthus—B. bicolor 

 and B. ceneas. 



