On the other hand we have the peacock, the green jungle cock, two blue ground thrushes (Arrenga cyanea and Myophonus flavirostris), the fine pink-headed dove (Ptilonopus porphyreus), three broad-tailed ground pigeons (Macropygia), and many other interesting birds, which are found nowhere in the Archipelago out of Java.
Insects furnish us with similar facts wherever sufficient data are to be had, but owing to the abundant collections that have been made in Java, an unfair preponderance may be given to that island.

This does not, however, seem to be the case with the true Papilionidae or swallow-tailed butterflies, whose large size and gorgeous colouring has led to their being collected more frequently than other insects.
Twenty-seven species are known from Java, twenty-nine from Borneo, and only twenty-one from Sumatra.

Four are entirely confined to Java, while only two are peculiar to Borneo and one to Sumatra.

The isolation of Java will, however, be best shown by grouping the islands in pairs, and indicating the number of species common to each pair.

Thus:-- Borneo ..