26 



THE CLASSIFICATION OF INSECTS 



analogy which exists between the lowest families of all the four great types of the 

 animal kingdom, and to consider these different types as rising from a common base, 

 in four different directions, to different heights of development, at which they differ 

 most widely. The analogy between the lowest Worms, with their embryonic char- 

 acters, the lowest Polyp-like Mollusca, and the lowest Radiata, is a far more promi- 

 nent feature in the animal kingdom than the collateral analogies which exist be- 

 tween their higher families. 



There is another feature in the affinities of the articulated animals, which, in 

 this classification, is more fully brought out, and which otherwise can hardly be 

 traced, the fact that the lower Crustacea resemble Worms nearly as much as the 

 young Insects ; and that here, again, we have in the three classes of this type a repe- 

 tition of the leading feature which we have noticed when comparing the four great 

 types together, the Worms beginning with a worm-like form, which they preserve 

 through life, the Crustacea ' beginning with a worm-like form, or with worm-like 

 inferior types, rising in their highest families to the type of pupae, and the Insects 

 beginning with a worm-like form, transforming into pupae, or, in other words, 

 assuming temporarily the type of Crustacea, and attaining finally to their highest 

 state, that of winged Insects. 



The wood-cut here annexed will give a graphic picture of this correspondence. 

 Fig. a represents Polynoe squamata, as a type of the class of Worms. Fig. b rep- 

 resents Branchipus stagnalis, as a type of the lower Crustacea, exemplifying at the 

 same time their analogy to the Worms and to the larval condition of the higher 

 Crustacea, of which Tig. d represents a characteristic species, the common shrimp of 

 Europe, Palemon serratus. Fig. c represents the caterpillar of Papilio Asterias, 

 which has a close resemblance to some of the higher Worms of the family of Tubi- 

 colae. Fig. e represents the pupa of the same Butterfly ; its analogy to the higher 

 Crustacea, which consists in the combination of the rings into two distinct regions, 

 cannot be overlooked. Finally, Fig. f represents a perfect Butterfly, in a state of 

 development which is not attained by any type of the great division of Articulata 

 except Insects. 



At this stage of the investigation, I venture to say that I have myself already 

 traced, to some extent, the analogy which exists between the various forms of 



