296 ZOOLOGY. 
It comprises the order of Merostomata represented at the 
present day by the king-crab, and the order T'rilobita, which 
is wholly extinct. The organization of the king-crab is so 
Fig, 263.—Cambarus pellucidus, the blind craw-fish of Mammoth Cave. Natural 
size, 
wholly unlike that of the Crustacea, when we consider 
the .want of antenne, the fact that the nervous system 18 
