HURTFUL ANIMALS ALLIED TO OR LIKELY 

 TO BE MISTAKEN FOR INSECTS. 



CASE CRUSTACEANS. 



The collection begins with two or three species of crustaceans 

 which are injurious to the horticulturist. These are not insects, 

 but they occupy the nearest and most projecting point of the great 

 region of the animal kingdom which lies next them. It is as if 

 two great continents lay opposite to each other, one inhabited by 

 insects and the other by crustaceans ; and as a traveller in begin- 

 ning the account of his journey starts with the port from which 

 he sailed, so it is desirable, in treating of insects, to begin by 

 endeavouring to trace the source from which they most probably 

 originally came. By doing so we shall connect the two kindred 

 nations of crustaceans and insects together. Starting from the 

 crustaceans we shall reach the insects through two routes or 

 I resting-points — islands, as it were, lying in the ocean between their 

 r respective continents, viz., the Spiders and their allies, and the 

 Thysanura and theirs, both lying much nearer the insect coast 

 than the crustacean — so near, indeed, that there need be no hesi- 

 tation in classing them among insects, which accordingly has been 

 done here, and yet so distinct that they cannot be so placed with- 

 out explanation and qualification. 



The Crustaceans, then, consist of that class of animals of which 

 the crab, lobster, and shrimp are our most familiar examples 

 They possess many characters which are common to insects, such 

 as an external skeleton or shell, articulated bodies and limbs, 

 and the same mode of articulation ; but are, for the most part, 

 sufficiently different in appearance from them. Some, however, 



