PROCEEDINGS OF SECTION D. 543 
condition were submitted to me for examination and identification 
by the hon. John Douglas, the Government resident at Thursday 
Island. The majority of the examples gathered were evidently 
the young of the Aeleagrina margaritifera. Mixed with them 
were, however, the young of the smaller black-lipped species 
usually identified with MMe/eagrina cumingii, and also those of a 
third non-commercial species not yet precisely determined, but 
apparently corresponding with Meleagrinu muricata. These 
shells, gathered from the Star of Peace, varied in size from one to 
three inches in diameter. Within the next few -days, while 
exploring the coral reefs in the immediate neighbourhood of 
Thursday Island at low spring tide, I had the good fortune to 
find several similar young living examples of the true mother-of- 
pearl shell, JZ. margaritifera. The smallest of these measured no 
more than one quarter of an inch, and the largest about two 
inches in diameter. These shells were, in all cases, attached to 
the under surface of loose coral rocks by a cable or byssus, 
consisting of a bundle of tough green threads. By severing this 
byssus carefully with a knife, the shells were secured without the 
slightest injury, and were brought in and kept alive for the 
purpose of studying their habits. Efficient aquaria for their 
conservation were extemporised out of a couple of huge clam 
shells, Z7idacna gigas, each having a capacity of several gallons, 
that ornamented the lawn of the Government Residency. Sea- 
water was brought up in buckets from the shore, aud renewed to 
them every day, the little pearl-shells adapting themselves with 
remarkable alacrity to their novel surroundings. About a dozen 
individuals, to which others were subsequently added, were 
maintained in health for several weeks under the conditions just 
described, and afforded the opportunity of observing and recording 
many important data. 
It was first observed that these young pearl-shells possessed 
the capacity of ejecting the portion of the byssus remaining 
imbedded in their tissues after they were separated from their 
primary attachment, and of secreting a new byssus, by which 
they affixed themselves to the nearest available anchorage. This 
was represented, in association with the specimens under observa- 
tion, by the interior surface of the clam-shells in which they were 
confined. In all instances, with rare exceptions, the re-attach- 
ment of the shells was effected on the immediate spot upon which 
they were placed when brought in from the sea, and to which 
anchorage they remained firmly fixed throughout the period of 
their confinement. The exceptions referred to were furnished by 
certain of the smallest-sized shells, one or two of which crept 
from the upper and re-attached themselves to the shaded 
under-surface of an empty oyster-shell, upon which they had been 
placed. A specimen in another instance moved for the space of 
a few inches before re-attaching itself by its new byssus. Two of 
