i) 
292 THE ENTOMOLOGIST. 
birds, and many others, nest inland, often amidst dense 
vegetation; and he believes they often carry seeds, attached 
to their feathers, from island to island for great distances. In 
the tropics they often nest on the mountains far inland, and 
may thus aid in the distribution even of mountain plants. 
Insects, on the other hand, are mostly conveyed by aérial 
currents, especially by violent gales; and it may thus often 
happen that totally unrelated plants and insects may be 
brought together, in which case the former must often perish 
for want of suitable insects to fertilise them. This will, I 
think, account for the strangely fragmentary nature of these 
insular floras, and the great differences that often exist 
between those which are situated in the same ocean, as well 
as for the preponderance of certain orders and genera. In 
Mr. Pickering’s valuable work on the ‘Geographical Distri- 
bution of Animals and Plants,’ he gives a list of no less than 
sixty-six natural orders of plants wneapectedly absent from 
Tahiti, or which occur in many of the surrounding lands, 
some being abundant in other islands,—as the Labiate at the 
Sandwich Islands. In these latter islands the flora is much 
richer, yet a large number of families which abound in other 
parts of Polynesia are totally wanting. Now much of the 
poverty and exceptional distribution of the plants of these 
islands is probably due to the great scarcity of flower- 
frequenting insects. Lepidoptera and Hymenoptera are 
exceedingly scarce in the eastern islands of the Pacific; and 
it is almost certain that many plants which require these 
insects for their fertilisation have been thereby prevented 
from establishing themselves. In the western islands, such 
as. the Fijis, several. species of butterflies occur in tolerable 
abundance, and no doubt some flower-haunting Hymenoptera 
accompany them; and in these islands the flora appears to 
be much more varied, and especially to be characterized by 
a much greater variety of showy flowers, as may be seen by 
examining the plates of Dr. Seeman’s ‘ Flora Vitiensis.’ 
Darwin and Pickering both speak of the great prepon- 
derance of ferns at Tahiti; and Mr. Moseley, who spent several 
days in the interior of the island, informs me that “at an 
elevation of from 2000 to 3000 feet the dense vegetation is 
composed almost entirely of ferns. A tree-fern (Alsophila 
Tahitensis) forms a sort of forest, to the exclusion of almost 
