1858.] TIIIRSK NATURAL HISTORY SOCIETY. 559 



and inter-communion of forms totally at variance with those 

 general opinions as to fixity which now reign in the scientific 

 world V 



It may be said, after all, that these things are not generally 

 known, and justly so, because they are not true. S. B. 



THIESK NATURAL HISTOEY SOCIETY. 

 Botanical Exchange Club. 



The monthly meeting of the Thirsk Natural History Society 

 was held on the evening of Tuesday, the 10th of August. Dr. 

 George Lawson, Professor of Chemistry and Natural History at 

 Queen's College, Kingston, Canada West, was duly elected a Cor- 

 responding Member. 



Mr. J. G. Baker communicated a paper entitled " Notes on the 

 Spring Botany of Wharfdale." 



" During the present spring I had the opportunity of staying 

 a week in Wharfdale, three days of which were in greater part 

 spent in excursionizing. Of what was noticed during the course 

 of these rambles it is my intention to give you some account this 

 evening ; but it will be needful to make a few preliminary expla- 

 nations relative to the physical geography and geology of the 

 dale, in order to render myself intelligible. 



" The stream rises on the slope of Cam Fell, nine miles from the 

 Avestern boundary of our county. For forty miles it flows towards 

 the south-east, during that part of its course declining in level 

 from 1200 to 220 feet; for thirty miles more it runs due east, 

 entering the Ouse at Tadcaster; for a little while at first its 

 course is amongst moorlands of the Yaredale division of the 

 mountain limestone series of strata, but soon it plunges amongst 

 the thick beds of the lower limestone, the same that forms the 

 floor of Ingleborough and the scars of Craven, and amongst 

 these it runs for nearly twenty miles. Several of the summits 

 that surround the earlier part of its course, Pennyghent, Foun- 

 tain's Fell, and Great Whernside, for instance, exceed 2000 feet 

 in elevation. As we proceed towards the south the gritstone 

 takes up more and more of the hilltops, till at last the stream 

 enters it at Bolton Bridge, and nothing else is seen after this till 



