THE SCORPIONS 



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the chelae, or great pincers, of large size and six jointed. The coxae of the four 

 pairs of legs are immovably united to form the floor of the cephalothorax, and 

 wedged in between those of the last two pairs there is a single sternal plate, the 

 shape of which is of considerable value as a characteristic in the classification of 

 these animals. The breathing organs consist of four pairs of sacs, of which the 

 cavities are filled up with a number of fine plates, arranged like the leaves of a 

 book, are placed upon the third, fourth, fifth, and sixth segments of the abdo- 

 men, and their apertures open upon the sternal or ventral plates of these segments. 

 ' 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 4oth or 45th 

 parallel of north latitude, the only extensive area of land in the Southern Hemi- 

 sphere 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 

 eight or nine 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 uni- 

 form, all the known forms being referable to four fami- 

 lies, namely, the Buthidce, Bothriuridcz , luridce, and 

 Scorpionidce. In the Buthidce the sternum of the cephalo- 

 thorax 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 luridcz agree with 

 the other two families in possessing 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 SPANISH YELLOW SCORPION, 

 in rocks of Secondary age, and only one has been recorded Buthus europ<eus. 



from Tertiary strata, this having been discovered in the (Natural size.) 



a. I,ower surface of the abdomen. 



amber beds of the Baltic. The strangest fact, however, showing combs and stigmata, 

 connected with fossil scorpions is the small amount of 



change the group has undergone, in spite of the enormous time that it has been in 

 existence. For instance, the Tertiary species named Tityus eoctznus does not differ 

 in any important particulars from existing forms; while those from the Carbonifer- 

 ous 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 Palccophonus is the best known, are unique in the 

 entire group in having the feet tipped with a single claw. For this reason the order, 



