SCORPIONS. 



215 



In addition to these stigmata, the abdomen bears a pair of curious organs called 

 combs, or pectines, which are placed upon the lower surface of the second segment, 

 and are very characteristic of the group. 



Scorpions are found almost all over the world to the south of the 40th or 

 45th parallel of north latitude, the only extensive area of land in the Southern 

 Hemisphere in which they do not occur being New Zealand. The largest known 

 forms occur in the tropical parts of Africa, especially on the shores of the Gulf 

 of Guinea, and in the southern districts of India. These are the big black 

 scorpions belonging to the genus Scorpio, which may 

 attain a length of 8 or 9 inches, measured from the 

 front of the head to the end of the tail. In structure 

 the various species and genera are, on the whole, 

 surprisingly uniform, all the known forms being refer- 

 able to four families, namely, the Buthidce, Bothriuridce, 

 luridce, and Scorpionidce. In the Buthidce the sternum 

 of the cephalothorax is small and triangularly-pointed 

 in front, in the Bothriuridce it is transversely linear, 

 and in the others it is broad and pentagonal ; but while 

 the luridce agree with the other two families in pos- 

 sessing two spurs on the articular membrane of the 

 tarsus, the Scorpionidce have but one. 



Scorpions are a very ancient group, well-preserved 

 remains of two genera having been discovered in the 

 upper Silurian beds of both Europe and North America. 

 In the Carboniferous period, too, they were evidently 

 abundant ; but no fossil forms have yet been discovered 

 in rocks of Secondary age, and only one has been recorded 

 from Tertiary strata, this having been discovered in the 

 amber beds of the Baltic. The strangest fact however, 

 connected with fossil scorpions is the small amount of change the group has under- 

 gone, in spite of the enormous time that it has been in existence. For instance, the 

 Tertiary species named Tityus eoccenus does not differ in any important particulars 

 from existing forms ; while those from the Carboniferous can only be distinguished 

 from them as a group by having the median eyes on the carapace in advance of 

 the lateral. In this feature they agree with the Silurian species ; but the latter, 

 of which Palceophonus is the best known, are unique in the entire group in 

 having the feet tipped with a single claw. For this reason the order, including 

 living and extinct species, has been divided into two sections, the Apoxypodes, 

 or those with pointed feet, including the Silurian Palceophonus, and the Diony- 

 chopodes, or those in which the feet are tipped with a pair of movable claws. 

 This last group is again divisible into the Anthracoscorpii, or scorpions of the 

 Coal period, in which the median eyes are in front of the lateral, and the 

 Neoscorpii, or recent forms, in which the median eyes are placed further back. 



In habits the different species seem to vary but little, most of them being 

 nocturnal and all of them exclusively carnivorous, feeding upon any living creature, 

 weak enough to be overpowered. They seem, however, to be largely dependent 



SPANISH YELLOW SCORPION, Bllthus 



eurojpceus (nat. size). 



a, Lower surface of the abdomen, 



showing combs and stigmata. 



