GENERAL CLASSIFICATION. 



Insects belong- to the phylum Arthropoda. a group of animals hav- 

 ing jointed bodies and jointed legs. In the same phylum are to be 

 found the following classes : 



1. Crustacea. — Water-breathing animals, with many legs and hard 



exoskeleton ; head and thorax united. 

 Examples : era])s. lobsters, crayfish 

 and sowl)ngs. 



2. Arachnida. — Land forms; 

 eight legs, head and thorax united. 

 Examples: scorpions (Fig. ]), sol- 

 pugids, spiders, mites (Fig. 2) and 

 ticks. 



8. Malacopoda. — Land f o r m s ; 

 bod>' worm-like with numerous legs. 

 A very peculiar animal which is sel- 

 dom met with. Exam|)l(': Peri pat us. 



4. Diplopoda. — I^and f o r m s ; 

 body long, cylindrical, many seg- 

 mented; two pairs of short legs to 

 each segment; antennie short. Ex- 

 ample: thousand-legged worms (Spi- 

 roholus). (Fig. 3.) 



5. Chilopoda. — Land forms; 

 l)ody long, fiat, many segmented ; one 

 pair of rather long legs to each seg- 

 ment ; antenna? long. Example : cen- 

 tipedes {Scolopendra) . (Fig. 4.) 



6. Insecta or Hexapod a. — 



Aquatic and terrestrial, but prima- 

 rily the latter. Body of the adults 

 divided into three distinct regions : head, thorax and abdomen. Adult 

 forms with six legs and many are winged. Transformations or meta- 

 morphoses occur in all except the two lowest orders, Tlnjsamira and 

 Collemhola. Example : insects. 



Fig. 1. — A scorpion, Buthus sp. 

 (After Folsom. ) 



-PI 



