138 YORKSHIRE NATURALISTS* UNION. 



tends to show that this change had already come into operation 

 some time before the commencement of the system of driving, 

 with which it has often been erroneously associated. Whether 

 this depends upon any alteration of climatic conditions, such as 

 has undoubtedly affected the growth of cereals, at certain eleva- 

 tions, I am not prepared to say. It is for you naturalists of 

 Yorkshire to determine by enquiry and comparison whether we 

 should be justified in attributing it to this cause. 



The origin and history of the grouse disease, doubtfully 

 attributed by Dr. Cobbold to the entozoic parasite named by 

 him Strongylus pergracilis, is but little known or studied. 



Already you have done much useful work. Mr. Nelson 

 and Mr. Taylor are still engaged upon their detailed and 

 annotated list of Land and Fresh-water MoUusca of Yorkshire : 

 this contains many interesting notes, and is especially valuable 

 for the care with which the distribution of the various species 

 has been studied. The Marine shells have received the 

 attention of Mr. Hey, and we are indebted to him for a useful 

 list published in the Naturalist. 



The Botanists have as usual, been very industrious, 

 headed by your late President, whose address on the ' Fathers 

 of Yorkshire Botany,' has been published during the past year. 

 They have also been ably represented by the Rev. H. H. Slater, 

 with his completed Flora of Ripon, by Mr. F. Arnold Lees, and 

 by Mr. Hobkirk, who has published a second edition of his well- 

 known Synopsis of British Mosses. 



In Ornithology, Mr. Eagle Clarke and Mr. Cordeaux have 

 been doing good work as Members of the Migration Committee 

 of the British Association. 



In Ichthyology, Mr. George Brook, who has devoted his 

 attention more especially to the embryology of fish, may be 



Trans.Y.N.U., 1883 (pub. 1885). Series D 



