470 



" In conclusion, I have to observe, that as the results of my 

 analyses differ more or less from others which have been stated 

 by chemists, I have been thus particular in detailing my me- 

 thods. The difference of our results only proves the variety 

 of proportions in which ancient manufacturers manipulated. 



" The balance employed in these analyses turns very per- 

 ceptibly with the thousandth part of a grain weight." 



Professor Allman read a memoir on the Natural History 

 of the genus Alcyonella. 



This memoir he proposed dividing under three heads. 

 The first was intended to embrace the literary history of the 

 genus, and to contain an enumeration of the several authors 

 who have in any way advanced our knowledge of it, with a 

 short analysis of the various memoirs in which it is treated. 

 The second head was to be devoted to its zoology, properly 

 so called, and to contain a description of the external charac- 

 ters, with the diagnosis of species and synonymy. In the third 

 it was proposed to give a detailed account of its anatomy and 

 embryology. 



It was in the month of April, 1741, that Trembley, in the 

 course of his celebrated researches in the history of the hydra, 

 discovered in the fresh waters near La Haye, an animal form 

 then quite new to science. It consisted of a lobed jelly-like 

 mass, from which protruded numerous polypoid bodies, cha- 

 racterized by the possession of an elegant crown of tentacula, 

 borne upon the margin of a crescent-shaped disk. This beau- 

 tiful tentacular plume is one of the most striking features in 

 the animal, and at once suggested the name oi Polype a pa- 

 nache, bestowed on it by its discoverer. 



The same zeal and fidelity of observation which had 

 marked all the previous labours of Trembley were now brought 

 to bear upon the investigation of this new animal; and by thus 

 making us acquainted with a very remarkable type of struc- 



