Yorkshire Naturalists' Club. 2675 



in the neighbourhood of Market Weighton : it is an adult male. A specimen of that 

 very rare bird, Tengmalm's owl (Noctua Tengmalmi) was shot about two years ago 

 at Hunmanby, by Admiral Mitford's keeper. A young specimen of the little gull 

 (Larus minutus) was shot at Bridlington Quay, about the 20th of October. Mr. 

 Graham exhibited the whole of the above specimens except the second. 



Mr. Baines showed a very interesting specimen of a pear which had thrown out 

 leaves from the side, and which also seemed to have made an effort to produce a stem. 

 This curious production was obtained this season from Scoreby. 



The Chairman exhibited specimens of the common southernwood {Artemisia 

 Abrotanum) in flower, obtained in St. Cuthbert's churchyard, in this city. He re- 

 marked that this plant, which so rarely flowers in this district, has, in that particular 

 spot, flowered regularly for some years past. 



A paper was then read by Dr. Morris, " On the power that certain Water-birds 

 possess of remaining partially submerged in Deep Water." Dr. Morris first showed 

 that diving-birds possess a wonderful power over their own specific gravity in the 

 water, and brought as proofs records of the habits of various birds, which had been 

 made by others, without reference to any particular theory, but simply as facts in the 

 history of the birds. He then considered the explanation which is usually given of 

 the phenomenon, viz., that the bird expels so much air from its body as to bring its 

 body to nearly the same specific gravity as water. This he brought several arguments 

 to disprove ; some from the anatomical character of the air-cells, and others from the 

 impossibility of the bird remaining unsuffocated with such a diminished quantity of 

 air. He then brought forward his own explanation of the fact, which was, that the 

 bird so compressed its body as to condense the air in the various cavities to. such an 

 extent as to remove its power of floating on the surface of the water. He first showed 

 that if air was condensed into any vessel, the floating power of the vessel was dimi- 

 nished, compared with the same vessel filled with air at the ordinary atmospheric 

 pressure. He then proved, by quotations from Audubon's ' American Birds,' that 

 various birds could, and did, voluntarily compress their bodies into less than one half 

 their usual bulk ; and, lastly, he showed that the paper nautilus obtained its power 

 of rising and sinking in water by a modification of this plan. Some further observa- 

 tions concluded the paper. Dr. Morris exhibited several diagrams to illustrate his 

 meaning. 



A discussion then followed, in which Messrs. Baines, Graham, W. Matterson and 

 the Chairman took part. Mr. Baines thought it might be explained by the action of 

 the birds' feet in the water, in striking up instead of down. The other gentlemen 

 generally were disposed to agree with Dr. Morris's explanation. 



Some general conversation was then carried on, after which the members sepa- 

 rated. 



December 5, 1849. — Edward Charlesworth, Esq., in the chair. 



A highly interesting memoir of the late Mr. Samuel Gibson, of Hebden Bridge, 

 was read by the chairman. 



Mr. Smallwood next brought forward a communication from J. Leckenby, Esq., 

 of Scarborough, in which he mentioned the curious fact which he had noticed of a 

 certain shell, which was abundant in a particular locality, having, after the lapse of 

 two or three years, without any apparent cause, entirely disappeared, its place being 

 supplied by a distinct but allied shell, which had previously been extremely rare in 

 that district. 



