The External and Internal Parasites of Domestic Animals #260551

The external parasites of our domestic animals nearly all belong to the great class of animals which we call Insects, but the internal parasites are, with few exceptions, representatives of the class of Worms. The division of the subjects of these lectures is, therefore, both convenient and natural. The class of Insects includes a far greater number of spe cies than any other class of animals, the number actually amounting to several hundred thousands, each country having a vast number peculiar to itself. They are also exceedingly diverse in habits, as well as in form and structure. In order to show the affinities of the insect-parasites and their position among other insects, it will be necessary to give a brief sketch of the whole class, with a few remarks on the more important peculiarities of their anatomy.