296 ENTOMOLOGY FOtl MEDICAL OFFICERS 



In some scorpions a similar spine is present at the end of the 

 tibia, or 5th segment — the tibial spur, or spurs. 



The mouth is a chink lying deep between the pedipalps, 

 and opens into a suctorial pharynx. The food consists of 

 insects and spiders, which are seized and held by the " hands " 

 of the pedipalps, are killed by a stab from the post-anal 

 sting, which is bent forwards over the back for the purpose, 

 and are then sucked dry. 



The vascular system is very complete, and the blood is 

 blue, as befits a group that has persisted with very little 

 change from Palaeozoic times. 



The reproductive organs open behind the genital flap on 

 the first abdominal sternum. In the male this flap consists 

 of two distinct halves, but in the female the two halves are 

 more or less united in the middle line. Usually also the 

 male is smaller than the female, and has a larger " hand " and 

 a longer " tail," and larger pectines. The female is viviparous, 

 and often takes some care of the young after they are born. 



The venom of the scorpion's sting causes much local 

 inflammation, and also in some species exercises general 

 physiological effects which, according to Calmette, are not 

 unlike those of the venom of Colubrine snakes, causing, when 

 injected into vertebrate animals, muscular paralysis, particu- 

 larly paralysis of the breathing-mechanism, and destruction 

 of the red blood-cells. Though small doses of the venom 

 have been observed, experimentally, to kill small mammals, 

 the sting of the scorpion is not likely to prove fatal to healthy 

 adult human beings though it sometimes causes severe shock. 

 Scorpion-sting may be treated in the same way as the stings 

 of venomous insects (p. 225). 



Scorpions are grouped in seven families, as follow : — 



Family i : Buthidce. The sternum is almost always 

 triangular ; in a few species it is pentagonal, and in these 

 species (as in many others of the family) the last pair, or 

 last two pairs, of legs have tibial spurs. The legs also have 

 a pair of pedal spurs, one of which often is double. Lateral 

 eyes, three or five on each side. Often there is a spine on 

 the swollen base of the " sting." About half the three hundred 

 (or thereabout) species of scorpions known belong to this family, 

 which is represented in all the warm parts of the world. 



