_The Place of Butterflies in the Animal Kingdom._--The animal kingdom, for purposes of classification, has been subdivided into various groups known as subkingdoms. One of these subkingdoms contains those animals which, being without vertebræ, or an internal skeleton, have an external skeleton, composed of a series of horny rings, attached to which are various organs. This subkingdom is known by naturalists under the name of the _Arthropoda._ The word _Arthropoda_ is derived from the Greek language and is compounded of two words, (_αρθρον_), meaning a _joint_ and (_πους_), meaning a _foot_. The _Arthropoda_ seem at first sight to be made up of jointed rings and feet; hence the name.
The subkingdom of the _Arthropoda_ is again subdivided into six classes. These are the following:
Class I. The _Crustacea_ (Shrimps, Crabs, Water-fleas, etc.).
Class II. The _Podostomata_ (King-crabs, Trilobites [fossil], etc.).
Class III. The _Malacopoda_ (_Peripatus_, a curious genus of worm-like creatures, found in the tropics, and allied to the Myriapods in some important respects).
Class IV. The _Myriapoda_ (Centipedes, etc.).
Class V. The _Arachnida_ (Spiders, Mites, etc.).
That branch of zoölogy which treats of insects is known as entomology.
The _Insecta_ have been variously subdivided by different scientific writers, but the following subdivision has much in it to commend it, and will suffice as an outline for the guidance of the advanced student.
For the most part undergoing only a partial metamorphosis in the development from the egg to the imago.
1. _Thysanura._ Suborders: _Collembola_ (Podura, Springtails). _Symphyla_ (Scolopendrella). _Cinura_ (Bristletails, etc.).
3. _Pseudoneuroptera._ Suborders: _Mallophaga_ (Bird-lice). _Platyptera_ (Stone-flies, Termites, etc.). _Odonata_ (Dragon-flies, etc.). _Ephemerina_ (May-flies, etc.).
4. _Neuroptera_ (Corydalis, Ant-lion, Caddis-flies, etc.).
5. Orthoptera (Cockroach, Mantis, Mole-cricket, Grasshopper, Katydid, etc.).
6. _Hemiptera._ Suborders: _Parasita_ (Lice). _Sternorhyncha_ (Aphids, Mealy Bugs, etc.). _Homoptera_ (Cicada, Tree-hoppers, etc.). _Heteroptera_ (Ranatra, Belostoma, Water-spiders, Squash-bugs, Bedbugs, etc.).
7. _Coleoptera._ Suborders: _Cryptotetramera_ (Lady-birds, etc.). _Cryptopentamera_ (Leaf-beetles, Longhorns, Weevils, etc.). _Heteromera_ (Blister-beetles, Meal-beetles, etc.). _Pentamera_ (Fire-flies, Skipjacks, June-bugs, Dung-beetles, Stag-beetles, Rove-beetles, Tiger-beetles, etc.).