_Lepidoptera._--The butterflies of the Nearctic region have lately been studied with much assiduity, and we are now able to form some idea of their nature and extent. Nearly 500 species belonging to about 100 genera have been described; showing that the region, which a few years ago was thought to be very poor in species of butterflies, is really much richer than Europe, and probably about as rich as the more extensive Palæarctic region. There is, however, very little speciality in the {123}forms. A considerable number of Neotropical types enter the southern States; but there are hardly any peculiar genera, except one of the Lycænidæ and perhaps a few among the Hesperidæ, The most conspicuous feature of the region is its fine group of Papilios, belonging to types (_P. turnus_ and _P. troilus_) which are characteristically Nearctic. It is also as rich as the Palæarctic region in some genera which we are accustomed to consider as pre-eminently European; such as _Argynnis_, _Melitæa_, _Grapta_, _Chionabas_, and a few others. Still, we must acknowledge, that if we formed our conclusions from the butterflies alone, we could hardly separate the Nearctic from the Palæarctic region. This identity probably dates from the Miocene period; for when our existing arctic regions supported a luxuriant vegetation, butterflies would have been plentiful; and as the cold came on, these would move southwards both in America and Europe, and, owing to the long continuance of the generic types of insects, would remain little modified till now. _Coleoptera._--Only a few indications can be given of the peculiarities of the Nearctic coleoptera. In Cicindelidæ the region possesses, besides the cosmopolite _Cicindela_, four other genera, two of which--_Amblychile_ and _Omus_--are peculiar to the West Coast and the Rocky Mountains. Of Carabidæ it possesses _Dicælus_, _Pasimachus_, _Eurytrichus_, _Sphæroderus_, _Pinacodera_, and a number of smaller genera, altogether peculiar to it; _Helluomorpha_, _Galerita_, _Callida_, and _Tetragonoderus_, in common with South America; and a large number of characteristic European forms. The Lucanidæ are all of European types. The region is poor in Cetoniidæ, but has representatives of the South American _Euphoria_, as well as of four European genera. Of Buprestidæ it has the South American _Actenodes_; a single species of the Ethiopian and Eastern _Belionota_, in California; and about a dozen other genera of European and wide distribution. Among Longicorns it possesses fifty-nine peculiar genera, representatives of five Neotropical, and thirteen Palæarctic genera; as well as many of wider distribution. _Prionus_ is the chief representative of the Prionidæ; _Leptura_ and _Crossidius_ of the {124}Cerambycidæ; _Leptostylus_, _Liopus_, _Graphidurus_, and _Tetraopes_, of the Lamiidæ, the latter genus being confined to the region. _Terrestrial and Fluviatile Mollusca._