because of the absence of gamma activity and because of the association
of Sr with Ca. Beta-counting of the
Y° daughter cf the Sr®° gave 16 dis-
integrations per minute per gram of
shell material, and the decay rate was
appropriate for Y°°. Thus, although
there were
undoubtedly other radio-
nuclides in the shell shortly after the
detonations, physical decay left detectable amounts of only Sr®°.
KELSHAW BONHAM
Laboratory of Radiation Biclogy,
University of Washington, Seattle 5
References and Notes
1. J. Brock, Z. Wiss. Zool. 46, 270 (1888), and
English translation by W. S. Dallas, Ann.
Mag. Nat. Hist. Ser. 6 2, 435 (1888).
2. C. M. Yonge, in Great Barrier Reef Expedition 1928-29, Scientific Reports [British Museum (Natural History), London, 1936], vol.
1, p. 283.
3.
» Proc. Zool. Soc, London 123, 551
(1953).
4.
Discovery 16, 154 (1955).
5 . H. V. Weiss and W. H. Shipman, Science
125, 695 (1957).
6. Specimen 302 was the smallest of six ranging
to 73 cm in length collected between 2 and
4 p.m. on 22 August 1964 about 100 m off the
north point of Airukiiji Island in water ! to
3 m deep. On the following day the soft
tissues were removed for radioassay. The dry
half-shell, brought to Seattle, was sectioned
on 21 September 1964.
. S. Glasstone, “Effects of Nuclear Weapons
(U.S. Atomic Energy Commission, Washing-
ton, D.C.. 1962), p. 674-676.
. M. K. Robinson. U.S. Geol. Surv. Profess.
Paper 260-D (1954), p. 281.
. W. S. Von Arx, ibid, 260-B (1954), p. 265.
. S&S. K. Wada, Oceanographic Max. 4(\), 23
(1952); Jap. J. Zool. 11, 273 (1954).
. K. M. Wilbur and L, H. Jodrey, Biol. Bull.
103, 269 (1952).
. Dr. A. D. Welander found specimen 128
about 11 a.m. on 12 August 1964 in water
less than 1 m deep within 20 m of the north
shore of Engebi Island, Eniwetok Atoll.
. Work
done
under
contract
AT(45-1)1389
with the AEC. . thank also Mr. Egil QOas
for preparing the thick and thin sections of
the shell, Miss Lorna Matson for the radioautographs, and Dr. Grant Gross for identification by x-ray diffraction of aragonite in
the shell.
7 June 1965
Ss