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Mr. Jacopson collected or observed: 16 species of Birds; 2 of 
Reptiles; 3 of Isopoda; 32 of Spiders; 8 of Crustaceans; 4 of 
Molluses, 1 of Worms and 191 of Insects. The common earth- 
worm was missing. Very important was the discovery of true 
land-snails, because to these animals is allotted a considerable 
part in zoo-geography, i.e. the geographical distribution of ani- 
mals. Hitherto it has been a canon of this science, that land- 
snails could not be carried across the sea, since they are very 
sensitive to salt. The received opinion was carried the length 
of saying that whenever the same species of snails occur in two 
‘islands, those two islands must certainly have been connected 
in the past. The finding of land-snails on Krakatau has cut away 
at a blow, what seemed the solid foundations of this theory; 
it is a new fact that will have to be thoroughly reckoned with. 
Mr. Jacosson draws the following conclusions, which are so 
important that I wish to quote them in full: 
I. To the spreading of most insects an arm of the sea some 
20 KM. wide is no appreciable obstacle; 
Il. Concerning the problem of island-fauna, at least as regards 
insects and reptiles, a more important part must be 
assigened to ocean-currents than has hitherto been done 
by most scientists; 
Ill. The presence of archaic forms of animal life, such as cen- 
tipeds and scorpions, may not count as a proof of the 
high age of islands; 
IV. Land-snails can also spread acros the sea, hence their 
presence on an island does not establish the conclusion 
that there must formerly have been land-bridges with 
other parts or continents; 
V. On an island robbed of its fauna by a volcanic eruption, 
or which is an entirely new formation, some species of 
the new fauna will increase at abnormal rates, if their 
natural enemies have not penetrated to the island along 
= - with them, provided the food they require (vegetable or 
a - animal) i is scaishie - Loomis in sufficient es - 
s were found by ~ Mr. Sowtea, but unlike ae 
