_Summary of Palæarctic Vertebrata._--Summarising these details, we find that the Palæarctic region possesses thirty-five peculiar genera of mammalia, fifty-seven of birds, nine of reptiles, sixteen of amphibia, and twenty-one of freshwater fishes; or a total of 138 peculiar generic types of vertebrata. Of these, 87 are mammalia and land-birds out of a total of 274 genera of these groups; or rather less than one-third peculiar, a number which will serve usefully to compare with the results obtained in other regions. In our chapter on Zoological Regions we have already pointed out the main features which distinguish the Palæarctic from the Oriental and Ethiopian regions. The details now given will {187}strengthen our view of their radical distinctness, by showing to how considerable an extent the former is inhabited by peculiar, and often very remarkable generic types. _Insects: Lepidoptera._--The Diurnal Lepidoptera, or butterflies, are not very abundant in species, their number being probably somewhat over 500, and these belong to not more than fifty genera. But no less than fifteen of these genera are wholly confined to the region. Nine of the families are represented, as follows:--1. _Danaidæ_; having only a single species in South Europe. 2. _Satyridæ_; well represented, there being more than 100 species in Europe, and three peculiar genera. 3. _Nymphalidæ_; rather poorly represented, Europe having only about sixty species, but there is one peculiar genus. 4. _Libytheidæ_; a very small family, represented by a single species occurring in South Europe. 5. _Nemeobiidæ_; a rather small family, also having only one species in Europe, but which constitutes a peculiar genera. 6. _Lycænidæ_; an extensive family, fairly represented, having about eighty European species; there are two peculiar genera in the Palæarctic region. 7. _Pieridæ_; rather poorly represented with thirty-two European species; two of the genera are, however, peculiar. 8. _Papilionidæ_; very poorly represented in Europe with only twelve species, but there are many more in Siberia and Japan. No less than five of the small number of genera in this family are wholly confined to the region, a fact of much importance, and which to a great extent redeems the character of the Palæarctic region as regard this order of insects. Their names are _Mesapia_, _Hypermnestra_, _Doritis_, _Sericinus_, and _Thais_; and besides these we have _Parnassius_--the "Apollo" butterflies--highly characteristic, and only found elsewhere in the mountains of the Nearctic region. 9. _Hesperidæ_; poorly represented with about thirty European species, and one peculiar genus. Four families of _Sphingina_ occur in the Palæarctic region, and there are several peculiar genera.