_Summary of Neotropical Vertebrates._--Summarizing the preceding facts, we find that the Neotropical region possesses no less than 45 families and more than 900 genera of Vertebrata which are altogether peculiar to it; while it has representatives of 168 families out of a total of 330, showing that 162 families are altogether absent. It has also representatives of 131 genera of Mammalia of which 103 are peculiar to it, a proportion of 4/5; while of 683 genera of land-birds no less than 576 are peculiar, being almost exactly 5/6 of the whole. These numbers and proportions are far higher than in the case of any other region. _Insects._ The Neotropical region is so excessively rich in insect life, it so abounds in peculiar groups, in forms of exquisite beauty, and in an endless profusion of species, that no adequate idea of this branch of its fauna can be conveyed by the mere enumeration of peculiar and characteristic groups, to which we are here compelled to limit ourselves. Our facts and figures will, however, furnish data for comparison; and will thus enable those who have some knowledge of the entomology of any other country, to form a better notion of the vast wealth of insect life in this region, than a more general and picturesque description could afford them. _Lepidoptera._--The Butterflies of South America surpass those of all other regions in numbers, variety and beauty; and we find here, not only more peculiar genera and families than elsewhere, but, what is very remarkable, a fuller representation of the whole series of families. Out of the 16 families of butterflies in all parts of the world, 13 are found here, and 3 of these are wholly peculiar--Brassolidæ, Heliconidæ, and Eurygonidæ, with a fourth, Erycinidæ, which only extends into the Nearctic {14}region; so that there are 4 families peculiar to America. These four families comprise 68 genera and more than 800 species; alone constituting a very important feature in the entomology of the region. But in almost all the other families there are numbers of peculiar genera, amounting in all to about 200, or not far short of half the total number of genera in the world--(431). We must briefly notice some of the peculiarities of the several families, as represented in this region. The Danaidæ consist of 15 genera, all peculiar, and differing widely from the generally sombre-tinted forms of the rest of the world. The delicate transparent-winged Ithomias of which 160 species are described, are the most remarkable. _Melinæa_, _Napeogenes_, _Ceratina_ and _Dircenna_ are more gaily coloured, and are among the chief ornaments of the forests. The Satyridæ are represented by 25 peculiar genera, many of great beauty; the most remarkable and elegant being the genus _Hætera_ and its allies, whose transparent wings are delicately marked with patches of orange, pink, or violet. The genus _Morpho_ is perhaps the grandest development of the butterfly type, being