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PACIFIC SCIENCE, Vol. IX, April, 1955 
warping, fitted with a small stop allowing the 
trap to dose only partially. Up to 35 traps 
were set at a time at 5 pace intervals shortly 
before dark. The trap line was brought in in 
the early morning and any specimens were 
placed in small cotton bags which were 
tightly tied so that ectoparasites could not 
escape. 
In the examination both the rats and the 
insides of the bags were searched for ecto- 
parasites and then external measurements 
were taken before the rats were skinned and 
sexed. Any skulls which were not too badly 
damaged were cleaned and preserved. The 
stomach and intestine was preserved in for- 
malin for later examination for food and 
parasites. 
The external measurements taken were: 
Total length — measured between tip of nose 
and tip of tail excluding hairs when the 
rat was lying on its back along the ruler. 
Tail — measured to tip when body was hang- 
ing at rt. angles to the ruler. 
Ear — measured from top of skull to tip. 
Foot c.u.— longest measurement from heel to 
claw. 
Foot s.u. — longest measurement from heel to 
end of flesh. 
Weight— measured in grams on a 250 gm. 
spring balance. 
Skull measurements were taken with vernier 
callipers except for measurements of the au- 
ditory bulla which were taken with an or- 
dinary ruler on a projected image of the skull. 
Skull measurements taken were: 
Total length — measured between parallels when 
skull was on a flat surface. 
Condylo-hasal L— from rear of occipital con- 
dyle to front edge of incisor base. 
Zygomatic breadth — across the greatest width, 
perpendicular to the long axis of the skull. 
Interorbital breadth— across parallels giving 
least measurement. 
Nasal— from back of suture to end of curved 
end. 
Diastema— from tooth base to tooth base; 
least measurement. 
Br. of rostrum — over incisor roots, perpendi- 
cular to long axis of skull. 
Br. of braincase— behind zygomatic arch. 
Depth of braincase — parallels giving least meas- 
urement. 
Mandible— horn articulation to end of bone 
on the inside. 
Maxillary toothrow — from toothbase to tooth- 
base. 
Mandibular toothrow — from toothbase to 
toothbase. 
The series of measurements was divided by 
locality— Manono and Upolu. The figures for 
each, and for the total series, were averaged 
and the standard deviations calculated. The 
Students t test was applied to the two series. 
RESULTS 
Food 
Turbet (1925) states that R. exulans eats 
"growing coconut, pineapple ..... all stored 
food, copra, drapery.” 
Stokes (1917) mentions that R. hawaiiensis 
in captivity will eat snails and living arthro- 
pods. Thus it appears that exulans type rats 
will eat both animal and vegetable foods. On 
Manono, signs of rats eating small fallen 
coconuts and large broken coconuts were 
widespread. At one spot a large pile of snail 
shells was discovered, each damaged and 
chewed. They were possibly eaten by rats. 
Unfortunately none was collected or closely 
examined. One instance was seen of an exulans 
eating at a pineapple during the day, and the 
pineapple proved to have been almost com- 
pletely hollowed out by rats. 
The stomach contents of the rats caught 
were examined for parasites and for recognis- 
able food debris. Of 29 examined 21 had 
some form of chitinous arthropod remains in 
them being identifiable in some instances as: 
ant (5); beetle (2); dipteran (2); spider (2); 
caterpillar (3), and centipede (1). Also, 
white vegetable debris was found in some. 
