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ZOOLOGY. 



It comprises the order of Merostomata represented at the 

 present day by the king-crab, and the order Trilobita, which 

 is wholly extinct. The organization of the king-crab is so 



Pig. 268. Cambarus pellucidus, the blind craw-fish of Mammoth Cave. Natural 

 size. 



wholly unlike that of other Crustacea, when we consider 

 the want of antennae, the fact that the nervous system is 



