iv 
Contents. 
PAGE 
Barometric Variability at Kimberley and Elsewhere. 
By J. R. Sutton, Sc.D., F.R.S.S.A 105 
On an Experimental Modification of Van der Waal's 
Equation. By John P. Dalton, M.A., D.Sc. (With 
Three Text-figures) 123 
A New Mimicry Plant, Mesembrianthemum lapidiforme, 
Marl. By R. Marloth. (With One Text-figure) . . 137 
Note on a Theorem of Ph. Gilbert's regarding the 
Differentiation of a Special Jacobian. By Thomas 
Mum, LL.D 139 
A Curious Mosquito, Culex theileri, Theobald. By G. A. H. 
Bedford, F.E.S 143 
The Triple Stellar System f Virgo and 2 1757. By R. 
T. A. Innes 145 
Preliminary Note on Some Phreodrilidae from the 
Wellington Mountains, South Africa. By E. J. 
GoDDARD, B.A., D.Sc 147 
On the Significance of the Somitic Constitution, Body 
Form, and Genital Apertures in the Hirudinea, in 
reference to the Arthropoda. By E. J. Goddard, 
B.A., D.Sc 148 
Note on Rosanes' Functions resembling Jacobians. By 
Thomas Muir, LL.D 157 
A Note on the Temperatures of the Air observed at 
MocHUDi. By R. J. Sutton, Sc.D., F.R.S.S.A. . . 163 
On the Porosity of the Rocks of the Karroo System in 
South Africa. By A. L. Du Toit, D.Sc, F.G.S. . . 169 
The Secular Variation of the Magnetic Elements in 
South Africa during the Period 1900-1913. By J. C. 
Beattie, D.Sc. (Plates i.-iii., and Two Text-figures) . 181 
Properties of Pfaffians, with their Analogues in Deter- 
minants. By Thomas Muir, LL.D. .... 205 
