Fauna of the Islands of Fernando de Noronha. 871 
charts usually represent the prevailing winds in this region as coming 
from the southeast. During the months of June, July, August, 
and September, they do come from that direction approximately, but 
during the remainder of the year they are usually from the northeast. 
The ocean currents shift slightly with these prevailing winds, so 
that when the winds from the northeast have prevailed for some 
time, the main body of the south equatorial current seems to be 
carried further south. Such changes throw upon Fernando at one 
time the currents from southwest Africa, and at others probably 
some of the counter-currents from the North Atlantic or from the 
Gulf of Guinea. 
Dr. Atfred R. Wallace, with whom the writer has spoken in 
regard to this question, suggests that these animals may have been 
introduced upon the floating trunks of trees from Africa. If we 
admit that such animals could endure so long an ocean voyage, the 
explanation satisfies the demands of the case as far as we are 
acquainted with them. 
The long existence of navigation as a science prior to the dis- 
covery of America, suggests that rats might have been carried here 
upon a wrecked vessel. But even admitting that the Amphisbena 
and the lizard might have come from some part of the Mediterranean, 
the chances of such animals finding their way upon board vessels 
are so extremely small that this hypothesis seems to have but little 
or no value. 
Tt has been suggested also that the islands of Fernando may have 
been joined to the Brazilian mainland at one time, and that by the 
cutting away of the isthmus joining the two, the island was thus 
left with the fauna found by its discoverers. The form of the 
Ocean’s bottom between the mainland and the island puts this 
hypothesis out of question. It was formerly supposed that Fer- 
nando had once been the northeastern point of Brazil, but the deep- 
Sea soundings by the Challenger expedition show that this is not 
true, and that Fernando is separated from the mainland by a trough 
More than 12,000 feet deep. In the light of these facts the ques- 
tion remains: where did these animals come from, and how did 
they get here? 
1! During my stay upon this island, in the monthsof July and August, 
the wind varied but little from due east, being at times from the E. N. 
E., and at others from the E. S. E. 
