358 ABSENCL OF TERKESTEIAL MAMMALS Chap. XII. 



of inimioTalion seoins to liavc been fully as impoptant as the 

 nature of the conditions. 



JIany remarkable little facts could bo given with respect to 

 the inhabit:iuts of oceanic islands. For instance, in certain 

 islands not tenanted Iiy a sing-le mammal, some of the endemic 

 plants have beautifully hooked seeds; and few relations arc 

 more manifest than that hooked seeds are adapted for trans- 

 portal in the wool or fin- of quadi-upeds. But a hooked seed 

 might be carried to an island by other means ; and the plant 

 then becoming modified Avould form an endemic species, Avhich 

 might still retain the hooks, Avhich would not form a more use- 

 less appendage than the shrivelled wings imder the soldered 

 elytra of many insular beetles. Again, islands often possess 

 trees or bushes belonging to orders elsewhere including only 

 herbaceous species ; now trees, as Alph. de Candolle has shown, 

 generally have, whatever the cause may be, confined ranges. 

 Hence trees Avould be little likely to reach distant oceanic 

 islands ; and an herbaceous plant, which had no chance of suc- 

 cessfully competing Avitli the many fully-developed trees grow- 

 ing on a continent, might, when established on an island, gain 

 an advantage by growing taller and taller and overtopping the 

 other herbaceous plants. In this case, natural selection would 

 tend to add to the stature of the plant, to whatever order it 

 belonged, and thus convert it first into a bush and then into a 

 tree. 



Absence of Batrachians and Terrestrial j[Tammals on Oce- 

 anic Islands. 



"With resjiect to the absence of whole orders of animals on 

 oceanic islands, I5ory St. Vincent long ago remarked that Ba- 

 trachians (frogs, toads, newts) are never found on any of the 

 many islands with which the great oceans are studded. I have 

 taken pains to verify this assertion, and have found it strictly 

 true, with the exception of New Zealand, of the Andaman 

 Islands, and perhaps of the Salomon Islands. But I have al- 

 ready remarked that it is doubtful whether New Zealand ought 

 to be classed as an oceanic island ; and this is still more doubt- 

 ful with respect to the Andaman and Salomon groups. This 

 general absence of frogs, toads, and newts, on so many oceanic 

 islands cannot be accounted for by their physical conditions; 

 indeed, it seems that islands are peculiarly well fitted for these 

 animals: for frogs have been introduced into Madeira, the 



