24 A HISTORY OF RECENT CRUSTACEA 



CHAPTER III 



MAGNITUDE 



In zoology, size attracts attention in comparison witli 

 two standards. Man contrasts the bulk of an animal 

 either with the average in his own order or with that of 

 the group to which the particular animal belongs. An 

 elephant is a huge beast, not in competition with a whale, 

 but with a human being. A hornet less than a man's 

 little finger is a monster beside a house-fly or a gnat. As 

 in all classes the majority of individuals conform pretty 

 closely to the average magnitude, the mind becomes 

 trained to regard the exceptional extremes with wonder, 

 often not unmingled with admiration when the mass is 

 not smaller but greater than common. Among the Crustacea 

 there are forms, not indeed surpassing all others in 

 diminutiveness, but at any rate so exceedingly small that 

 the sharpest eyes could perhaps never have found out that 

 they were crustaceans without the aid of the microscope. 

 Here it is that the philosophical naturalist sometimes finds 

 chief reason to marvel, in perceiving the whole machinery 

 of life, enabling active locomotion, nutrition, and repro- 

 duction, with senses, a power of choice, and the capacity 

 for feeling pleasure and pain, all packed away as neatly 

 and conveniently as possible in so extraordinarily small a 

 casket. For preliminary studies creatures of more con- 

 siderable compass hold an obvious advantage, and with 

 most observers it is rather the giants of an order than 

 the dwarfs that are deemed especially remarkable and 

 worthy of the notice which they are fitted readily to 

 engage. Some of the old writers probably understood 



