8 NATURAL ARRANGEMENT OF INSECTS. 



arranged under two great groups or classes ; the first 

 comprising the Aptera, or wingless insects, further dis- 

 tinguished by undergoing that particular metamorphosis 

 which tends to give an increased number of legs to the 

 perfect insect. The second is the Ptilota of the phi- 

 losopher of Stagira, or the winged insects, whose meta- 

 morphosis tends to give wings to the adult. These we 

 place as the typical and the sub-typical groups of the 

 Annulosa. Thus it may be said that in a leech, a tape- 

 worm, a barnacle, a spider, and a butterfly, we have the 

 respective types of the five great divisions of annulose 

 animals, in the order here mentioned. 



(8.) Our next proposition is, that this assemblage or 

 sub-kingdom (equal in rank to the vertebrated division) 

 forms a circle of affinity more or less complete, the only 

 hiatus being in that part which intervenes between the 

 Annelides and the Ptilota. It will be seen, however, 

 that this hiatus is of no great consequence in reference 

 to our present purpose ; because as the Annelides come 

 next to fishes, and there is no other break in thfe chain 

 from them to the Ptilota, we establish the series of the 

 five types, and can readily suppose an intervening form 

 yet undiscovered among the thousands that still remain 

 unknown, which may unite the aquatic Annelides to- 

 the aquatic Neuroptera, the most aberrant class of the 

 Ptilota. Commencing, then, with the Annelides, the 

 resemblance between the earth-worms and many of the 

 Vermes is sufficient to satisfy the ordinary observer of 

 their close resemblance ; while the fact of Lamarck 

 having had no hesitation in placing them together, on 

 account of their general similarity of structure, will 

 have due weight with the scientific naturalist. So little 

 is yet known of the genuine annulose Vermes, that it 

 would be premature to say in what manner they are 

 connected to the Cirrhipedes; but the precise station of 

 these latter in the circle of the Annulosa is rendered 

 certain: — first by their forming the passage to the 

 Radiata, and, secondly, by their absolute union to the 



