1909. } FAUNA OF COCOS-KEELING ATOLL. 135 
built. The nasals extend posteriorly to the anterior margin of the 
orbit, are 15°5 mm. long, and 2°8 mm. wide at their broadest 
part. Basal length of skull 35-38 mm.; greatest breadth 18 mm.. 
Interorbital constriction, least breadth 6 mm.  Interparietal, 
length 5 mm., breadth 10 mm. Length of base of anterior root 
of zygoma 6 mm. Palate, length 20 mm.; breadth, outside m* 
9 mm., inside m’4 mm. Palatine foramina 8 mm., extending 
1 mm. behind the anterior edge of m'—this is a constant feature. 
Alveoli (back of incisors to m') 12 mm. Upper molar series. 
6°5 mm. Incisors pale yellow in the lower jaw, orange in the 
upper jaw. 
The measurements in millimetres of a series of specimens are 
as follows :— 
| 
Head ; | 
and Tail. me | ae | von Forearm.) Sex. | 
| Body. oot. | (tibia). oot. | 
i} | | 
1 190 120M) MELONI BO 20 See a 
2 207 268 40 AS eile 20 33 4 
3 195 200 40 50) 20 SOPe ers 
4 195 | 191 38 42 22 25 a 
5 205 | 215 40 52 19 34 e 
6 1S 185 40 50 18 32 3 
7 192 | 216 40 | 50 19 34 ef 
8 200 | 205 40 45 20 30 Q 
9 180 | 185 AOne iss 20 3U fe) 
10 163 | 158 39 AD 22 29 Q 
11 150 155 38 39 22 27 e) 
12 147 149 36 385) belies 24, Q 
13 215 230 42 45 | 22 36 Q 
14 198 | 202 39 AS We SX) 32 2 
TSW ISZ 1-490 39 Asis | is 32 Q 
peneen || 270 160 SaWey Aoi galas 20 38 fe) 
lice gle 120 130 a He BB aye ale/ 32 2 
| } 
Habits.—The rat is very abundant on Pulu tikus, and although 
it has been steadily trapped, and hunted by dogs, for the last four 
years, it does not appear to diminish in numbers. As many as 
forty will still be taken in wire traps beneath the Telegraph 
quarters in a night, and outside the little area of the station the rat 
swarms everywhere. It is by no means a house rat, and although 
it is common in and around the houses it is still more abundant 
in the outlying parts of the island. It is splendidly adapted to 
its environment; it has altogether given up burrowing, and it. 
lives in the piles of coconut husks and in the crowns of the palms. 
It is certain that, at times, the young are born at the tops of the 
palms, which are 60 to 70 feet high. The rats ascend the trees with 
the greatest ease, and they run from one palm to the next, across: 
the interlacing fronds, very much after the fashion of the squirrel. 
They are by no means strictly nocturnal, doubtless from their 
long freedom from any enemies, and they are to be seen running 
about at all times of the day. They feed almost entirely upon 
the fallen coconuts, and all the nuts that I have ever seen opened 
