178 



Dr. A. A. Gould presented, in the name of Lieut. 

 Preble, U. S. Navy, a specimen of Dlpsas plicata, upon 

 the inner surface of which were a number of beautiful 

 elevated pearly figures, representing the god Boodh, pro- 

 duced during the lifetime of the animal, upon nuclei 

 placed within the shell. The following account of the 

 process, by Dr. Magowan of Ningpo, accompanied it: — 



The introduction of the pearl nuclei is an operation of consid- 

 erable delicacy. The shell is gently opened with a spatula of 

 mother of pearl, and the free portion of the mollusc is carefully 

 separated from one surface of the shell with an iron probe ; the 

 foreign bodies are then introduced between the points of a bifur- 

 cated bamboo stick, and placed in two parallel rows upon the 

 mantle or fleshy surface of the animal. A sufficient number 

 having been placed on one side, the operation is repeated on the 

 other. Stimulated by the irritating bodies, the suffering animal 

 spasmodically presses against both sides of its testaceous skele- 

 ton, keeping the matrices in place. This being done, the animals 

 are deposited one by one in canals, streams, or pools connected 

 therewith, five or six inches apart, at depths of from two to five 

 feet, in lots of from five to fifty thousand. If taken up a few 

 days after the introduction of the moulds, they will be found 

 attached to the shell by a membranous secretion, which at a later 

 period becomes impregnated with calcareous matter ; and finally 

 layers of nacre are found deposited around each nucleus, the 

 process being analogous to the formation of calculous concretions 

 in animals of a higher development. A ridge of nacre generally 

 extends from one pearly tumor to another, connecting them all 

 together. 



About six times in the coui'se of the season several tubs of 

 night soil are thrown into the reservoir for the noui'ishment of 

 the animals. Great care is taken to prevent goat manure falling 

 in, as it is highly detrimental to the mollusc, preventing the 

 seci'etion of good nacre, or killing them, according as the quantity 

 is great or small. 



In November the shells are carefully collected by hand. 



Dr. Storer presented a specimen of the Trumpet Fish, 

 {Centriseus scolopax.,) caught at Provincetovvn, the first 



