The Order includes many species of Insects, though in Britain it is poorly represented: we have only about forty species, and this small number includes some that are naturalised. Only a few of the forty extend their range to Scotland. A revision of the species found in Britain has recently been made by Mr. Eland Shaw.[127] In continental Europe, especially in the south, the species become more numerous; about 500 are known as inhabitants of geographical Europe. In countries where the face of nature has been less transformed by the operations of man, and especially in the tropical parts of the world, Orthoptera are much more abundant. The lowest number at which the species now existing on the surface of the earth can be estimated is 10,000. This, however, is probably far under the mark, for the smaller and more obscure species of Orthoptera have never been thoroughly collected in any tropical continental region, while new forms of even the largest size are still frequently discovered in the tropics. We shall treat the Order as composed of eight families:— Series, _Cursoria_: hind legs but little different from the others. { 1. Forficulidae—Tegmina short, wings complexly folded; body { armed at the extremity with strong forceps. { 2. Hemimeridae—Apterous: head exserted, constricted behind. { 3. Blattidae—Coxae of the legs large, exserted, protecting { the lower part of the body. { 4. Mantidae—Front legs very large, raptorial, armed with spines. { 5. Phasmidae—Mesothorax large as compared with the prothorax. Series, _Saltatoria_: hind legs elongate, formed for leaping, their femora usually thickened. { 6. Acridiidae—Antennae short, not setaceous, of not more than { 30 joints, tarsi three-jointed. { 7. Locustidae—Antennae very long, setaceous, composed of a { large number of joints, tarsi four-jointed. { 8. Gryllidae—Antennae very long, setaceous, tarsi two- or { three-jointed. The first five of these subdivisions are amongst the most distinct of any that exist in the Insecta, there being no connecting links between them. The three groups forming the {202}Saltatoria are much more intimately allied, and should, taken together, probably have only the same taxonomic value as any one of the other five groups.