Criticises at length the concept of submerged continents attaching islands to the mainland in the recent period. Notes drastic alteration of geography required, the dissimilar species on opposite shores of continents, and differences between volcanic islands and mountains of mainland areas. Admits sea-bed subsidence, but not enough to engulf continents. Denies that theory can explain island flora and fauna.

Considers Edward Forbes’s idea a check on study of dissemination of species.