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Monday, 7th March 1853. 

 Sir T. M. BRISBANE, Bart., President, in the Chair. 



The following Communications were read : — 



1. On the Species of Fossil Diatomacese found in the Infu- 

 sorial Eai'th of Mull. By Professor Gregory. 



The author, after some general remarks on the Infusoria gene- 

 rally, and especially on their occurrence in the fossil state, mentioned 

 that the earth in question had been discovered by the Duke of Ar- 

 gyll at Knock, near Aros in Mull, and its geological position briefly 

 described by him to the Society, two years ago. The author had 

 undertaken an examination of it, and had found it to contain, be- 

 sides Phytolitharia, silicified pollen of grasses and coniferse, and 

 spicules and gemmules of fresh-water sponges, the unprecedented 

 number of about 60 species of Diatomacese. He had consulted the 

 Rev. W. Smith, who had observed in it the following 59 species, all 

 belonging to fresh water, which he named, the names being those of 

 his forthcoming Synopsis, and one species which he cannot at pre- 

 sent refer to any known form. 



