224 
PACIFIC SCIENCE, Vol. II, July, 1948 
Carolines, which average at least 16 per 
cent Fe 2 0 3 . 
The associated clays were also tested on the 
portable thermal analysis unit and were found 
to contain less than 5 per cent gibbsite. Two 
samples of clay derived from the weathering 
of basalt were also tested by this method. One 
contained a very small amount of gibbsite, the 
other none. 
The discovery of bauxite on Truk was not 
unexpected, for bauxite deposits of some sort 
are known to occur on most of the high vol¬ 
canic islands in the western Pacific. Deposits 
have long been known to occur on Ponape and 
Kusaie, the two islands which geologically are 
most nearly comparable to Truk. To date, the 
trachytic material from which this bauxite has 
been derived has not been found by the writer 
on any of the other bauxite-bearing islands, and 
in this respect the deposit is unique. In fact, 
this parent material has not been identified on 
any of the other islands in the Truk group itself. 
This does not mean that it does not occur, but 
merely that the reconnaissance made in 1946 
was very brief, and that not all of the islands 
in the group were visited or studied in any 
detail. Yossii (Imp. Acad. Japan, Proc. 13: 74- 
77, 1937) reports trachyte from Ponape, but 
not from any other island in the former South 
Seas Mandate. Bauxite deposits, some of them 
rather low in iron, occur on Ponape, but their 
relation to the parent rock was not observed 
by the writer. 
Although the presence of bauxite on Truk 
is interesting from a scientific standpoint, the 
deposit is too small and the bauxite is of too 
low a grade to be of commercial importance 
at the present time. No further examination 
of the islands for bauxite alone appears to be 
warranted; however, a study of the occurrence 
and extent of the deposits should be a part of 
any general geological survey of the group.— 
Josiah Bridge, Geologist, U. S. Geological Sur¬ 
vey. (Published by permission of the Director, 
U. S. Geological Survey.) 
Holes in the Webs of Shearwaters 
DURING the COURSE of examining young and 
a few adult Wedge-tailed Shearwaters (Puf- 
finus paciftcus cuneatus) on Rabbit and Moku 
Manu Islands just off Oahu, in the fall of 1947, 
23 of 38 birds checked at random were found 
to have holes in the webs of their feet. These 
holes varied in number and size from several 
large ones (see photograph) to one or more 
very small ones. As many as seven holes were 
found in a single foot. Sometimes, as is also 
shown in the photograph, the holes were mar¬ 
ginal and formed gaps on the edges of the webs. 
The holes were first found in young a few 
weeks old (smaller young were not observed). 
They rarely appeared in the feet of 25 marked 
young which were observed from the age of 
about 1 month to 3 months. Once formed in 
these older young, the holes remained essen¬ 
tially unchanged. Apparently the webs became 
tougher and thicker with age and less easily 
torn. Large holes, in particular, seemed to have 
been acquired during the first few weeks after 
the young hatched. 
The explanation of the holes has not been 
conclusively determined. Small scabs have been 
noted on the feet of a number of young birds. I 
have picked off such scabs, as a bird might, and 
Fig. 1 . Wedge-tailed Shearwater’s foot. Life size. 
thus made or disclosed small web perforations. 
(Of 6 pin pricks made in the webs of 2 young, 
1 small permanent hole resulted.) Further peck¬ 
ing or scratching at such a small hole might 
well lead to a larger one, for a tear in the web 
soon rounds out as the edges contract and heal. 
The cause of the original small scabs, if they 
may be taken as the starting point in hole de¬ 
velopment, seems most likely to be the bites of 
the large hippoboscid flies (? Olfersia sp.) that 
very commonly infest the young. Small carni¬ 
vorous ants are present and might cause irrita¬ 
tion that would be pecked. Fighting between 
