72 SCORPIONS 



the first two of the four pairs of walking legs have maxillary plates 

 and harbour glands that secrete digestive enzymes. 



Scorpions live in hot and tropical countries. In Europe several 

 species are found in Greece, Italy, Spain and the Balkans and at 

 least one has a range extending into southern Germany. On the 

 American continent they are found from Patagonia to the more 

 southern of the United States. Their geographical distribution has 

 been made the subject of several studies and is interesting because 

 scorpions are a very ancient group, are not readily dispersed to new 

 localities and consequently are of great importance in biogeographi- 

 cal research. They are absent from many islands, including New 

 Zealand. 



The order is divided into six families, of which the most impor- 

 tant is the Buthidae with more than 600 species including Buthus 

 occitanus, the common yellow scorpion of France and the Medi- 

 terranean region, and A^idroctonus australis the fat-tailed scorpion 

 of North Africa, while the species of Centrums and Tityus are 

 Neotropical. The Diplocentridae are found in the Palaearctic 

 region, the isle of Sokotra in the Gulf of Aden and Mexico, the 

 Scorpionidae in Africa, Madagascar, Asia and Australia, while the 

 Vejovidae occur mostly in Asia and America. The Chactidae have 

 a somewhat similar distribution and include the small black Euscor- 

 plus spp. of southern Europe and the Mediterranean, while the 

 Bothriuridae live in Australia. Most species have a very limited 

 range, excepting Isornetrus 7naculatus, which is ubiquitous in the 

 warmer parts of the globe, and Scorpio maurus which extends from 

 the Atlantic to India. Few are found at high altitudes, but S. 

 maurus and Buthus occitanus occur in the Atlas Mountains and 

 Euscorpius germanus in the Tyrol. On morphological grounds the 

 Buthidae can be separated from the remaining families of scor- 

 pions, and it is believed that the two groups may have evolved in- 

 dependently, perhaps even since the Silurian epoch. 



General behaviour 



Scorpions resemble other Arachnida and insects in having an 

 impervious integument and efficient powers of water retention. 

 (Cloudsley-Thompson, 1956). They are markedly nocturnal but 

 this habit cannot be dictated primarily by the need to avoid dry air. 



