IV. 



Scorpions and their Geographical Distribution. 



IT is a well-established fact that Scorpions have been in existence 

 since the Middle Silurian era. But, unfortunately, almost all 

 that we know of their geological history is furnished by a few speci- 

 mens from beds of this age, and by a few more discovered in strata 

 of the Coal period. It is also well known that the structural diffe- 

 rences between the recent and the carboniferous fossil forms cannot be 

 justifiably regarded in the light of an advance in organisation. In 

 fact, as has already been more than once pointed out, these animals 

 furnish an admirable example of a persistent type of life. From the 

 persistence of structural characters, a persistence of habit may be 

 inferred. At all events, there is little, if any, evidence that these 

 animals, in the past days of their history, have ever gained a livelihood 

 by means other than those employed at the present day. There is no 

 reason for thinking that they have ever adopted an aquatic or 

 arboreal mode of life, or have ever been dependent upon running or 

 leaping powers for the capture of prey or avoidance of enemies ; nor 

 is there any foundation for the belief that any species has ever been 

 helped in the struggle for existence by the assumption of any of those 

 disguises of identity that are generally spoken of as protective 

 colouration, or mimicry. That an abundance of time to become 

 specialised into any number of strange forms has been granted them, 

 must be admitted on all hands ; but, perhaps, no fact connected v/ith 

 the existing species of Scorpions so forcibly strikes the student as the 

 wonderful closeness of the connection between the different genera 

 that have been established. There is, naturally, a considerable amount 

 of structural variation, if two extremes be selected for comparison ; yet 

 the extremes are linked together by such a series of intermediate 

 types that the division of the order into sharply-defined minor groups 

 becomes a task of no small difficulty. Now, this is hardly what we 

 should have looked for in a group of such vast antiquity. We should 

 rather have expected to find the living population of Scorpions com- 

 posed of a larger, or smaller, number of more or less isolated forms, 

 the annectent types between which would have to be sought for in 

 the records of their past geological history. But, considering that, 

 for obvious reasons, there is practically no record of Scorpion-life 

 between the Carboniferous times and our own day, it is, perhaps, not 



2 A 



