100 Mr. B. Clarke on the Stmcture and Affinities of 



excrescentia latere interiore, dum exterius latus perforatur.^ * I 

 once told him that I had discovered his secret in his ov,'u writings ; 

 he seemed to be embarrassed, made no inquiry as to the passage 

 to which I referred, and broke off the conversation/' There is 

 no doubt that attached half-pearls may be produced, when the 

 shell is bored through l)y a worm, or artificially. These hemi- 

 spherical pearls are often of large size ; Dr. Mobius describes 

 three of nearly half an inch in diameter. 



Imperfect pearls are usually produced artifically hy inserting 

 foreign substances between the mantle and the shell. The 

 Chinese appear to be the principal operators in this wa3^ Ac- 

 cording to Grill they insert a string of 5 or 6 spherules of 

 mother-of-pearl into Mussels in a lake near Canton, by which 

 they are covered with a nacreous layer in the course of a year. 

 These pearls are used for embroidery, in which their defects may 

 be concealed. The Chinese also produce hemispherical pearls 

 upon the inner surface of the shells of Barbata plicata [Dipsas 

 plicatus, Leach), by inserting mother-of-pearl forms between the 

 shell and mantle, and specimens of this shell are not uncommon, 

 bearing numerous attached pearly figures of Chinese deities, 

 formed upon metal moulds in the same situation. Dr. Gray 

 also says that the Chinese produce nearly globular pearls in this 

 mollusk, around silver wire. 



Dr. Kelaart states that he has " doctored^' some Pearl Oysters 

 " according to the plan adopted by the Chinese, in the case of 

 the large iresh-water Mussel," but does not describe the parti- 

 cular process employed by him. At the end of the copy of his 

 Report which he has had the kindness to forward to us, he has, 

 however, appended a manuscript note, dated the 7th December, 

 1857, in the following words : — " Since writing the above, I 

 have established the fact, that good pearls can be made by the 

 oysters which are treated as the Chinese treat the fresh-water 

 Mussel. If the Ceylon Government will not establish artificial 

 Pearl-banks, other Governments may try the experiment, and 

 the Arripo bank be in time valueless." 



X. — On the Structure and Affinities of jMyricacese, Platanese, 

 Altingiacese c/it/ Chloranthacese. ByB. Clarke, Esq.,r.L.S.&c. 



[With a Plate.] 



Myricace.e. 



The ovary of this family having engaged the attention of some 

 most accurate observers, by whom it is regarded as simple, the 

 following remarks on its structure may prove interesting, espe- 

 cially as the stigmas, which are ordinarily two, are occasionally 

 * This passiiije is sui)pressp(l in the tenth edition. 



