ON THE TRANSFORMATION OF INSECTS. 15 



convenient character for the primary division of annulates is 

 the number of legs. 



Hexapoda have, in their final state, six articulated legs. They 

 have no power to reproduce a leg, if accidentally lost. Two 

 distinct tribes are included in this group : — 



Tribe I. — Tetraptera, or winged insects. 

 II. — Aptera, or wingless insects. 



Octopoda have, in all their states, eight articulated legs. They 

 have power to reproduce a leg, if accidentally lost. Two distinct 

 tribes are included in this group : — 



Tribe III. — Arachnoida, or spiders. 

 IV. — AcAROiDA, or acari. 



Anisopoda have, in all their states, the number of the legs varying 

 from that of the Octopoda to that of the Myriapoda. They have 

 power to reproduce a leg, if accidentally lost. Two distinct tribes 

 are included in this group : — 



Tribe V. — Malacostraca, or crahs, lobsters, and similar shell- 

 fish, with simple legs. 

 VI. — Entomostraca, aquatic animals, somewhat similar, 

 but having legs with branchial appendages. 



Myriapoda have an indefinite number of legs in their final state ; 

 generally more than twenty, but only six in their first state. 

 They have the power to reproduce a leg, if accidentally lost. One 

 tribe only is included in this group : — 



Tribe VII. — Myriapoda, or centipedes. 



Of these seven tribes, the Tetraptera offer the most obvious 

 characters in their metamorphosis for farther subdivision. It 

 may be remarked as a singular fact, without applying it to any 

 theory, that the perfect Aptera frequently represent the imper- 

 fect Myriapoda, likewise the perfect Myriapoda represent 

 the imperfect Tetraptera. The Tetraptera, like the Condy- 

 lopoda, constitute four perfectly distinct groups, three of 

 which are, in like manner, double groups, and the fourth is 

 most heterogeneous in its contents, but from carrying the organs 

 of sense, &c. to greater perfection, superior to the others. 



