4.64 Royal Society. 



ploy the acrid juice to poison their arrows. T. 60, a singular but not hand- 

 some plant of the natural order Compositce, Synedrella nodijlora,^ rendered 

 interesting, however, by an admirable analysis of the fructification. The 

 three following plants are devoted to as many species of a new genus of 

 Ferns, the Pleopeltis of Humboldt, and coming respectively from America, 

 Africa, and northern India. The first, t. Gl, the Pleopeltis angitsta, Hum- 

 boldt; the second, t. 62, Pleop. ensifolia. Hook., a new species gathered at 

 the Cape of Good Hope; and the third, t. 63, Pleopeltis nuda, was sent to 

 our author fi-om Nepal by Dr. Wallich. 



XCIV. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



May 29.— 'T'HE reading of Mr.W. S. Harris's Description 

 -^ of a Magnetic Balance, &c. was resumed and 

 concluded ; and that of the following paper commenced : A 

 Case of Pneumato- Thorax, with Experiments on the Absorp- 

 tion of different Kinds of Air introduced into the Pleura; by 

 John Davy, M.D. F.R.S. 



June 5. — Dr. Davy's paper was concluded, and the follow- 

 ing was read : On Fossil Shells, in a letter to the President ; 

 by L. W. Dillwyn, Esq. F.R.S. 



The reading of the following paper was begun : Observa- 

 tions and Experiments on the daily Variation of the Horizontal 

 and Dipping Needles, under a reduced directive Power ; by 

 Peter Barlow, Esq. of the Royal Military Academy. 



June 12. — The reading of Professor Barlow's paper was 

 concluded ; and the following paper was read : On Bitumen 

 in Stones; by the Right Hon. George Knox, F.R.S. 



June 19. — The titles and a small part of the contents of the 

 following papers were read : 



On Astronomical Refraction ; By James Ivory, Esq. F.R.S. 



Tables of certain Deviations which appear to have taken 

 place m the North Polar Distances of some of the principal 

 fixed Stars; by John Pond, Esq. F.R.S. Astronomer Royal. 



On a Case of Pneumato-Thorax in which the Operation of 

 Tapping the Chest was performed, with additional Observa- 

 tions on Air found within the Body, &c. ; by John Davy, 

 M.D. F.R.S. 



Account of Experiments made with an Invariable Pendulum 

 in New South Wales ; by Major Gen. Sir Thos. Brisbane, 

 K.C.B. F.R.S. 



Astronomical Ooservations made at Paramatta ; by Mr. 

 Rumker. 



The Second Part of Mr. Bell's paper On the Nerves of the 

 Orbit. 



On Algebraic Transformation as deducible from First Prin- 

 ciples 



