544 PROCEEDINGS OF SECTION D. 
the smallest examples, about one-quarter inch in diameter, which 
were temporarily kept in a wide-mouthed bottle, were observed to 
creep, with the aid of their slender protrusible foot, a little dis- 
tance up the side of the bottle, and to which they then made 
themselves secure by the secretion of a new byssus. This byssus, 
or anchoring cable, is secreted a thread at a time; during its 
exudation it is of the consistency of liquid glue, but rapidly 
hardens in the water. The byssus of living examples of the true 
pearl-shell, AZe/eagrina margaritifera, was in all cases observed, 
whether young or old, of a glassy sea-green hue, and the number 
of threads or strands of which the entire cable is composed usually 
averages from thirty to forty. It may be mentioned here that 
the extemporised aquaria, represented by two large clam-shells, 
in which the young pearl-shells were confined, were left exposed 
on the hillside in front of the Residency, and fully open to the 
action of the south-east monsoon, which, at the period of the 
experiments conducted, August and September, blew strongly 
and continuously, and thus received the thorough re-oxygenisation 
of the water in which the shells were kept. The only additional 
precaution taken for their welfare was the placing of a board 
over the top of the clam-shells to screen the water with its living 
contents from the direct rays of the tropical midday sun. 
The facts that were determined in association with the experi- 
mental culture of the young shells, as just described, may be thus 
summarized :—1l. It was conclusively demonstrated that the 
pearl-shell, in its young condition at least, firmly attaches itself 
to submarine objects by means of a so-called byssus, or anchoring 
cable. 2. That in the event of injury, the primary byssus can 
be ejected and a new one secreted. This fact carried with it the 
demonstration that the animal was capable at will of separating 
itself from its original fulcrum, and of re-attaching itself else- 
where. 3. While the young animals were found to possess the 
capacity of locomotion, such locomotion was shown to be of a 
feeble character and rarely exercised. In this respect the habits 
of the pearl-shell were found to coincide to a considerable extent 
with those that have been observed of ordinary mussels, genus 
Mytilus, and the wing-shells, genus Avicula. Active locomotive 
functions similar to those of the scallop-shells, genus /ecfen, and 
an allied type, genus Zz#za—both of which can transport them- 
selves to considerable distances by the opening and closing of 
their valves—are certainly not possessed by the pearl-shell, 
Meleagrina margaritifera, and have been incorrectly ascribed to it 
by many of the divers and owners of shelling-boats. 
The information gathered concerning the life habits of the 
young pear]-shell was next extended to that of the more matured 
and adult individuals. This was accomplished chiefly through 
the acquirement of materials obtained in an excursion made in 
the G.S. Aldatross to one of the most prolific shelling-grounds in 
