102 ON THE FAUNA OF CHRISTMAS ISLAND. [ Feb. 2, 
where; the other, J/us nativitatis, more adapted for burrowing, 
was for the most part confined to the higher ground. Last year, 
in spite of continual search, not a single specimen of either species 
could be found in any part of the island. This complete disap- 
pearance of two such common animals seems to have taken place 
within the last five or six years, and to have been the result of 
some epidemic disease, possibly caused by a trypanosome, intro- 
duced by the ship-rats. These are a variety of Mus rattus, and 
have been introduced in considerable numbers, though they do 
not seem to have spread to the remoter parts of the island at 
present, at least to any great extent. The disappearance 
therefore of the native forms cannot be due to direct competition 
with the intruders, but must be the result of disease, a con- 
clusion supported by an observation made by the medical officer, 
Dr. McDougal, who told me that some five or six years ago he 
frequently saw individuals of the native species of rats crawling 
about the paths in the daytime, apparently in a dying condition. 
Thope that it will be possible to obtain information as to whether 
any trypanosome or other pathogenic organism occurs in the blood 
of the imported rats. 
‘Of the other native mammals the shrew (a variety of Croct- 
dura fuliginosa) is probably also extinct, at least no specimen 
was either seen or heard during my visit. The large fruit-bat 
(Pteropus natalis) is more numerous than formerly, at least near 
the settlement, probably in consequence of the much larger 
number of fruit-trees now to be found there. Cats have been 
introduced, and are becoming numerous; in some cases they 
have taken to the woods, and occasionally cause great destruction 
among the poultry which are reared in large numbers. 
‘The native land-birds all seem to be as numerous as formerly. 
The large fruit-pigeon (Carpophaga whartoni), which is. used 
for food, is protected during the breeding-season, and at other 
times the number killed is limited so far as possible. These 
birds have not yet acquired any fear of man, and allow themselves 
to be snared by hand as easily as ever. The frigate-birds do not 
nest in the neighbourhood of Flying Fish Cove in anything like 
such numbers as formerly, but are still very numerous elsewhere. 
The yellow tropic-bird (Phaethon fulvus) seems to have increased 
in numbers. No introduced bird has obtained any footing on 
the island. 
“No changes of importance were noticed among the native 
Invertebrates; but the large Scolopendra, of which a very few 
individuals were noticed during my first visit, is now much 
more numerous. Probably many insects have been introduced, 
but until my collections have been fully worked out, nothing can 
be said on this point. 
““ A large number of plants have been introduced, and probably 
the clearing of the forest and cutting of roads will enable them 
to spread much more rapidly in the future than they have done 
in the past. Already the papaia and chillies have extended 
