Fauna of the Islands of Fernando de Noronha. 865 
have been cut off from the main island and left upon Ilha Rapta 
when this separation took place. Whether they would sur- 
vive upon the other islands, Ilha do Meio, Ilha Raza, ete., would 
depend entirely upon whether the conditions upon them for 
survival were favorable or otherwise, and their existence or non- 
existence at intermediate points would have but little bearing upon 
the question. It may be asked, in case this theory is correct, why 
we find no rats upon Ilha Rapta. This is possibly to be attributed 
to their having been entirely exterminated by the convicts. 
Ilha Rapta is, in-a sense, one of the institutions of the penal 
settlement. It has an area of less than a square mile, no wood, 
though it is said to have been wooded formerly, but little potable 
water, and, compared with the main island, it is very low. e 
soil is extremely fertile, and excellent sweet potatoes grow wild 
over a large part of it, while the waters about its shores swarm 
with edible fish and enormous sharks. When, at the time of my 
visit, and prior thereto, a prisoner upon the main island became 
particularly unmanageable, he was banished to Ilha Rapta, which 
was regarded as a sort of insanctum insanctorwm, where he was left 
to his own devices for subsistence. 
I learned from the commandant that formerly large numbers of 
convicts were banished to Ilha Rapta at the same time. Now it 
was generally understood when I was upon Fernando that rats 
were not uncommonly eaten by the convicts on the main island, 
and as those sent to Ilha Rapta were left to do as they 
saw fit, they were often reduced to great straits for food, and it 
does not seem improbable that they ate rats, if rats ever existed 
there, Then, too, when efforts were made to raise crops here, the 
, Tats, had they existed in such numbers as upon the main island, 
would simply have rendered such crops impossible. The area of 
the island is so small, and the places in which rats could hide so 
few, that their extermination would not be an impossible or even 
a very difficult matter. 
I trust that the novelty of it will be sufficient apology for a short 
digression here to describe the method employed by the convicts on 
Ilha Rapta to catch fish. A hook attached to a line about 150 
feet long, baited with a fresh sardine or the white skin of some 
other fish, is thrown out into the water and quickly drawn ashore. 
