Proceedings of Societies. 169 



loaded with sweets, it has also used similar precautions to prevent its 

 being corrupted with exhalations of a contrary nature ; and to effect this 

 purpose, it employs an infinite number of insects, which class of animals 

 in conjunction with the fungi, may be called the depurators and scaven- 

 gers of nature." 



No. 27. September. 



Tab. 131. Nostoc cceruteum. t. 132. Leangium? Trevelyani, anew, 

 very curious, and rare species, discovered by the gentleman whose 

 name it bears, t. 133. Ortkotrichum Ludwigii, a recent addition to the 

 muscology of Britain, t. 134. Erysiphe Pisi, the cause of mildew on 

 that valuable species of esculent vegetable, the common Garden Pea, 

 infesting its leaves with a fine white film, t. 135. Cucurbitaria cinnaba- 

 rina. 



No. 28. Octooer. 



Tab. 136. Stromatosphttriafragiformis var. laevis. 1. 137. Orthotrichum 

 speciosum, another species new to Britain, t. 138. Sphceria rosella. t. 13!). 

 Peziza Wauchii, nov. sp. t. 140. Myrothecium Carmichaelii, nov. sp. 



No. 29. November. 



Tab. 141. Erineum griseum et clandestinum. 1. 142. Thelepltora quer- 

 cina. t. 143. Helvetia leucophaa. t. 144. Sclerotium scutellatum et se- 

 men. t. 145. Weissia splachnoides. 



Art. XXX.— PROCEEDINGS OF SOCIETIES. 



1 . Proceedings of the Royal Society of Edinburgh. 



November loth. — The Royal Society resumed its sittings for the winter. 



A paper was read by Mr. Haidixger, on the Determination of the 

 Idea of the Species in Mineralogy, according to the principles of Profes- 

 sor Mohs. 



The purpose of this paper is to show, that in the determination of the 

 species, no attention should be given to the chemical properties of bo- 

 dies, that is, to those which are observable while a mineral ceases to 

 exist ; but that every property should be taken into consideration which 

 minerals exhibit in their natural state. Bodies which agree in this re- 

 spect either entirely, or in which the differences in their characters may 

 be joined by continuous series, belong to one and the same species. 

 Chemical considerations on the composition of minerals are then only 

 conclusive, if the species has been previously determined; and a com- 

 prehensive knowledge of them can only be obtained, if we do not slight 

 any of the properties of minerals, which has but too frequently occurred, 

 by supposing that in mineralogy there is nothing so satisfactory as the 

 chemical composition of a body. 



