TllK AMKKKWN MONTHLY' |.l!inu:.rv, 



Uk- lesser parts arc as well. The Ic^s cutisii,i uf a luaiiv-jointod 

 ilistal-positiim tarsus bcariiijj two claws at the tip and of a lar<je 

 tibia aiul teiiuir, Init tlie reiiiur is joinetl to the body by a ioiiji joint, 

 not a sliort one as in the jjrasshopper. The winvjs. too. are on the 

 nicso ami tneta-thorax, tlie protliorax beinjj j^rown to the nieso 

 thorax. The nioutli-parts, too, present the same parts, viz.. 

 lips and mandible and niaxilhe, though not like those of the grass- 

 hopper in tletail. 



These comparisons can be extended to the internal anatomy of 

 these specimens, and we tind that the organs there located cor- 

 responil in position and relation with the various systems of the 

 grassln)pper ; thev can be extended beyond the series here taken 

 up to a vast number «)f other such animals, and in them all the 

 same principles prevail. Hut it is not possible to demonstrate this 

 plan ot' bodv among all animals dwelling together. Thus the 

 spi<ler, slug, saw-bug, and manv other animals can be found where 

 crickets live, ami vet these bodies cannot be analyzed into such 

 parts as are found in the forms just consideretl. Vhc spider, for 

 instance, has a boily which is divided into two regions ; has no 

 compound eyes and four pairs of simple eyes ; has no antenna-, 

 no wings, no mouth-parts, no distinct head ; has four pairs of legs 

 used for walking, and two pairs of appendages in front which find 

 no compeer among the animals we are studying. Hence the plan 

 we have discovered is a somewhat exclusive one ; all animals 

 which possess it we assign to a group we call a class, called in- 

 sects, while we regard the various sorts under the class as orders. 

 If we compare the katydid with the other insects we have studied, 

 we shall find it considerably more like the grasshopper and cricket 

 than anv others, and these, togctlier with tiie roach and others, 

 make up the order Orthoptcra. In the same one we can sec that 

 the potato-lnig, firefly, pea weevil, lady-bug. and many other very 

 familiar animals are all somewhat like the May-beetle, and belong 

 in a ditVerent order from the Orthoptera., while ants and bees go 

 with the wasp, and the mosquito and fly belong together. Orders 

 are divided \x\\.o families, and these again \x\X.o genera ., and these 

 into species. Each of these groups has its name, and in speaking 

 technicallv of any insect or any other animal we do so bv giving 

 the name of the genus and species to which it belongs. The de- 

 partment of zoology which is devoted to such comjiarisons as this 

 is called systematic zoology or classification. 



There are still other departments of zoological study of which 

 we can here do little more than to mention two which have ref- 

 erence to the distribution of animals over the earth's surface or 

 geographical distribution and the date of the appearance of ani- 

 mals in the progress of the geologic history of the earth, or palajo- 

 zocilogy. The genera and species of animals are often rather 

 local in their geographical range. Northern Europe and North 

 America both have the same genera of grasshoppers, but have 

 few if am of the same species, while some families, on the other 



