284 ARTHROPODS. 



of the East Indies attains a length of six inches, but the 

 majority are much smaller. They feed on the blood and 

 juices of Insects and other small animals. It is often said 

 that scorpions will commit suicide when surrounded by fire 

 or when otherwise fatally threatened, but to this it is 

 answered — first, that their poison does not affect them- 

 selves ; secondly, that they do not sting themselves ; thirdly, 

 that they could not if they would ! 



The body consists of an unsegmented cephalothorax and 

 a twelve-segmented abdomen. The abdomen includes two 

 distinct regions, — a broad anterior seven-segmented " meso- 

 soma," and a narrow five-segmented "metasoma," at the 

 end of which there is a post-anal " telson " or sting containing 

 a double poison gland opening at the sharp tip. There is a 

 firm cuticle of chitin ; and an interesting internal piece of 

 skeleton (the entosternite) partly chitinoid, but also resemb- 

 ling fibro-cartilage, lies between the anterior end of the 

 gut and the central nervous system, and serves for the 

 attachment of muscles. 

 The appendages are — 



(i) Small chelate chelicerae or falces just above the 



mouth. 

 (2) Large chelate pedipalps which seize the prey. 

 In some cases they produce sounds by rasping. 

 (3-6) Four pairs of walking-legs. The basal joints 

 of the first two pairs of legs are utilised in 

 connection with the mouth. 

 Apparently equivalent to a pair of appendages is a small 

 double lid or operculum covering the genital aper- 

 ture on the first abdominal segment. 

 Apparently of the nature of appendages are the comb- 

 like, apparently tactile, pectines on the second 

 abdominal segment. Six other pairs of abdominal 

 appendages are present in the embryo scorpion, 

 but they abort. 

 The respiratory organs consist of four pairs of "lung- 

 books," " pulmonary sacs," or " chambered tracheae," lying 

 in the broad part of the abdomen, and opening by slit-like 

 stigmata on the third to the sixth abdominal segments. Each 

 is like a little purse with many compartments. Air fills the 

 cavity, but there is blood round about. They are believed 



