Miscellaneous. 143 



Mr. Evans directed attention to a curious instance of the effects of 

 the graft upon the stock, which had occurred in a tree at Morning- 

 side House, the residence of Mr. J. Deuchar. The tree in question 

 is Pi/rus Aria, grafted upon P. aiicuparia as a stock. Its entire 

 height is 18 feet, and the stock forms a clean trunk to the height of 

 4 feet, where the union of the graft and stock is conspicuously shown. 

 At 1 3 inches from the base of the trunk there are shoots of P. au- 

 cuparia, and at the height of 1^ foot, branches of P. Aria appear 

 (being 2| feet below the point of junction), while farther up the trunk 

 a branch has been accidentally taken off, which is believed to have 

 been P. aucuparia. 



Mr. M'Nab exhibited a peculiar creeping form of Sarothamnus 

 Scoparius (common broom), which had been sent from Aldemey ; 

 but he could give no farther information respecting it, as the specimen 

 was not accompanied by a letter. 



MISCELLANEOUS. 



THE VELVET-LIKE PERIOSTRACA OF TRIGONA. 



Dr. Fleming, at a late meeting of the Royal Physical Society, made 

 some remarks on the velvet-like periostraca of Trigona ventricosa of 

 Gray. lie mentioned that " he had brought this subject under the 

 notice of the Society, in the first place to correct an erroneous state- 

 ment which Mr. Gray, of the British Museum, had made on his 

 authority in the ' Annals and Magazine of Natural History,' No. 22, 

 for October 1849, and in the second place to combat views which 

 Mr. Gray had advocated as to the origin of the so-called velvet-like 

 periostraca. It was stated that an imperfect experiment by burning 

 had indicated the siliceous nature of the crust, and that the con- 

 clusion thus drawn was mentioned to Mr. Gray. Subsequent expe- 

 riments however had demonstrated it to be carbonate of lime. Dr. 

 Fleming then adverted to the composition, structure, and position of 

 the mass, as indicating a substance wholly unconnected with the in- 

 habitant of the shell, organically, but exhibiting the characters of an 

 imperfectly developed sponge of the genus Grantia. He exhibited 

 examples of two different species with similar traces of Grantia, and 

 concluded by producing three specimens of the common Pecten oper- 

 cularis with a band of sponge around the margin, similar in position 

 to that on the Trigona, but composed of siliceous spicula, and be- 

 longing to the genus Halichondria. The fringe of a Zoophyte grow- 

 ing on the ligamental or siphon margin of the shell of the Trigona, 

 referable to the genus Laomedia, was pointed out as supporting the 

 opinion that the velvet-like coat of calcareous spicula was likewise 

 unconnected with the secretions of molluscan life." 



Note. — The correction respecting the nature of the spicula is im- 

 portant, but I cannot agree with the Professor as to their origin. I 

 might be more easily convinced if I saw a perfect specimen of a spe- 

 cies of Trigona without the velvet-like coat, or with the coat assuming 

 a branched or foliaceous sponge-like form. — J. E. Gray. 



