124 GEOGRAPHICAL DISTRIBUTION. 



tinues its journey upwards. The dorsal and 

 anal fins can be folded up and received into a 

 cavity of the body. 



How exactly does this structure fit it for this 

 extraordinary instinct. These fins assist it in 

 certain parts of its route, and, when not em- 

 ployed, can be packed up so as not to hinder its 

 progress. The lobes of its gill-covers are so 

 divided and armed as to be employed together, 

 or separately, as hands, for the suspension of 

 the animal, till, by fixing its dorsal and anal 

 fins, it prepares itself to take another step ; all 

 showing the Supreme Intelligence and Almighty 

 hand that planned and fabricated its structure, 

 causing so many organs, each in its own way, to 

 assist in promoting a common purpose. The fan 

 palm, in which this animal was taken by Daldorff, 

 grew near the pool inhabited by these fishes. He 

 makes no mention, however, of their object in 

 these terrestrial excursions ; but Dr. Virey ob- 

 serves that it is for the sake of small Crustaceans, 

 on which they feed. 



I shall name only one more animal that 

 migrates for the great purpose of reproduction, 

 and this is not the least interesting of them ; and, 

 though it does not furnish so large a supply of 

 food to the countries it passes through, as the 

 migratory fishes, still it is useful in that respect : 

 the animal I allude to is the land-crab. 



Several, indeed, of the crabs forsake the waters 



