Geological Society, 53 



the abdomen, -? T \h of an inch ; length of the cephalothorax -fa ; breadth 

 fa ; breadth of the abdomen fa ; length of an anterior leg £ : length of a 

 ]eg of the third pair fa. 



The male resembles the female in colour, and the relative length of its 

 legs is the same as in that sex. The third and fourth joints of the palpi 

 are short, the latter being much the stronger, and prominent in front ; the 

 fifth joint is oval, convex externally, concave within, comprising the sexual 

 organs, which are highly developed, complicated in structure, and of a dark 

 reddish brown colour. 



I found this minute species in considerable abundance in the month of 

 March 1833, on iron rails at Crumpsall Hall; and in the autumn of the 

 same year I procured specimens in the vicinity of Llanrwst. 



Tribe, ORB™,! Latreil]e> 

 (jrenus, Lmyphia, J 



Linyphia pusilla. 



As this spider bears a striking resemblance to Linyphia minuta t \t will suf- 

 fice to point out those particulars in which it differs from that species. It 

 is smaller, of a more slender form, and the colour of the legs and palpi is 

 plain, yellowish brown. The upper part of the abdomen is pale brown, 

 and along the middle extends a series of strongly marked, brownish black, 

 angular lines, having their vertices directed forwards; the sides and under 

 part are dark brownish black, and the plates of the spiracles are of a brown 

 colour. The female has no cylindrical appendage in connexion with the 

 sexual organs. 



Length, from the anterior part of the cephalothorax to the extremity of 

 the abdomen, -^th of an inch; length of the cephalothorax fa ; breadth 

 fa > breadth of the abdomen fa ; length of an anterior leg £ ; length of a 

 leg of the third pair £. 



The abdomen of the male is more slender, and darker coloured than 

 that of the female, but the relative length of its legs is the same; their ab- 

 solute length, however, is greater, an anterior one measuring |th of an 

 inch. The third and fourth joints of the palpi are short, the latter being 

 very strong, and prominent in front; the fifth joint is convex externally, 

 concave within, comprising the sexual organs, which are highly developed, 

 complicated in structure, and of a red-brown colour. 



This species is common in autumn on rails in the vicinity of Manchester, 

 and in the neighbourhood of Llanrwst. 



Crumpsall Hall, Feb. 10, 1834. 



X. Proceedings of Learned Societies, 



GEOLOGICAL SOCIETY. 



Mr. GreenougJCs Anniversary Address. 

 [Continued from vol. iv. p. 454.] 



AMONG the subjects which have for some years past engaged the 

 thoughts of geologists, none perhaps has excited so general and 

 intense an interest as the Theory of Elevation. I shall avail myself, 

 therefore, of the present occasion to lay before you a connected 

 statement of the scattered facts and opinions upon which it rests. 



On entering upon this subject, it is necessary to understand di- 

 stinctly what is meant by Elevation. Definitions have recently 

 been decried, I think unwisely. The formation of definitions, 

 it has been said, and the establishment of unerring distinctions 



