226 Annals of the Philosophical Club 



appeared to have this effect to some extent, but hardly so 

 much as he had anticipated. 



1884. Jan. I7th, 330th meeting. Dr. Giinther described 

 the curious fate of a small fish of the Indian Archipelago 

 the fierasfer which inhabited, as a commensal, the body 

 cavity of certain holothurians. 1 For some unknown reason, 

 one of them had got between the mantle and the shell of a 

 pearl oyster (Avicula margaritifera), by which it was killed, 

 and, before it could decay, was covered with a layer of 

 mother of pearl, thin enough to let it be seen in an apparently 

 perfect state through its transparent shroud. 



Feb. I4th, 33ist meeting. Professor Stokes said that 

 some crystals of chlorate of potash had been sent to him 

 which showed by reflexion splendid colours. The mineral 

 crystallizes in the oblique system, usually in plates perpendi- 

 cular to the plane of symmetry. The tint differs from one 

 crystal to another, and alters with the inclination of the 

 crystal. When a face is viewed at a given angle, and rotated 

 in its own plane, the tint disappears twice in a complete 

 rotation. He had found that all crystals exhibiting this 

 colour-phenomenon had a very thin twin structure present, 

 the individuals being about one-thousandth of an inch thick. 

 To reflexion from this the colours are due, but he was not 

 yet in a position to give a complete explanation. 



May 22nd, 334th meeting. Professor Moseley exhibited 

 a specimen of Utricularia vulgaris, from marshes near 

 Oxford, which he had received from a young naturalist, son 

 of a tradesman in that city, showing that its bladder traps 

 are capable of catching newly-hatched fishes, numbers of 

 minute roach being held in various positions by them. 2 



June 1 2th, 335th meeting. According to Sir J. H. Lefroy,, 

 information had been received from Zanzibar that Mr. 

 Joseph Thomson had returned in safety from exploring the 

 region east of the Victoria Nyanza. 



Oct. 23rd, 336th meeting. Professor Tyndall said that 



1 Perhaps the subject of the engraving in The Royal Natural History , 

 vol. v. page 438. (Giinther, Proc. Zool. Soc. 1886, page 318.) 



2 For more details, see Nature, vol. xxx. page 81. 



