Careful study of insular faunas, such as that of Madeira by T.
This difficulty will disappear as the strata become better known; but at present each of the silted-up lakes has to be studied separately, for we cannot expect so close a correspondence in their faunas and floras as is found in the more crowded and smaller basins in central Europe.
Agassiz continues, however, in terms characteristic of the creationist school: " But this connexion is not the consequence of a direct lineage between the faunas of different ages.
As man cannot easily avoid introducing parasites, and must keep domestic animals and till the land, a certain disturbance in aboriginal faunas is absolutely unavoidable.
Prof. Kayser suggests that there was also a Pacific basin more extensive than at present; this is borne out by the similarity between the Cambrian faunas of China, Siberia and Argentina.