PEARL AND PEARL-SHELL FISHERIES. 215 



unto themselves wings and flee away. As the experiments demonstrated, none of the three 

 theories was in precise accord with the facts. 



By a fortunate coincidence, the author arrived at Thursday Island, on his first official visit, 

 August 6, 1889, at a period that enabled him almost immediately to acquire important informa- 

 tion concerning the life-habits of this shell-fish. A few weeks previously, a diver who had been 

 employed to examine the bottom of the storage hulk. Star of Peace, with a view to repairs, 

 found growing upon it a quantity of shells which were pronounced by him to be the 3'oung of the 

 true pearl-shell. No attempt was made to keep the shells alive. They were merely dried and 

 cleaned, and in that condition submitted to the author 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 Meleagrina margaritifera . Mixed with them, however, were 

 the young of the smaller black-lipped species, here distinguished by the title of Meleagrina nigro- 

 margmata, and also those of a third non-commercial species not yet precisely determined, but 

 apparently corresponding with Meleagrina muricata. These shells, gathered from the Star 

 of Peace, varied from one inch 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, the author obtained several similar young living examples of the true mother-of-pearl 

 shell, M. margaritifera. The smallest of these measured no more than a 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 author secured the shells without 

 the slightest injury. They were brought in and kept alive for a stud}' of their habits. Efficient 

 aquaria for their conservation were extemporised out of two huge clam-shells, Tridacna gigas — 

 each having a capacity of several gallons — that ornamented the lawn of the Government Residence. 

 Sea water was brought up in buckets from the shore, and renewed to them every day ; the little 

 pearl-shells adapting themselves with remarkable alacrity to the novel environment. 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 embedded in their tissues after they were separated from 

 their primary attachment, and of secreting a new byssus, by which they afifixed themselves to 

 the nearest available anchorage. The latter was furnished, in the specimens under observation, 

 by the inner of the clam-shells in which they were confined. In very nearly all instances 

 the re-attachment of the shells was effected to the immediate spot upon which they were 

 placed when brought in from the sea, to which anchorage they remained firmly fixed through- 

 out the period of their confinement. The exceptional cases were furnished by certain of the 



