XVI CONTENTS 



Posthumus (O.). Etapteris Bertrandi Scott, a new etapteris from the upper 

 carboniferous (lower coal-measifres) from England, and its bearing to 

 stelar-morphoiogica! questions. 669. 



Potassium (A relation between the spectra of ionized) and argon. (Second 

 comm.). 498. 



Power series (On a generalisation of Tauber's theorem concerning). 216. 



— (A theorem concerning) in an infinite number of variables, with an 

 application to Dirichlet's series. 278. 



— (On) of the form : x"» — xfi -|- xPü — ... 456. 



Propylene (Researches on the addition of water to ethylene and). 321. 



Psychology. F. F. Hazelhoff and Miss H. Wiersma : "On subjective 

 rhythmisation." 462. 



Pyridylpyrroles (The synthesis of some). 426. 



Radio-active (Is caesium)? 575. 



Raniniens nouveaux (Description de) des terrains tertiaires de Borneo. 777. 



Rays (On the plane pencils containing three straight lines of a given alge- 

 braical congruence of). 522. 



Reptiles (On the development of the shoulder-girdle and episternum in). 15. 



Researches (Magnetic) v. Magnetic researches. 



Resistance (On the electric) of pure metals, etc. XII. Measurements concern- 

 ing the electric resistance of indium in the temperature field of liquid 

 helium. 504. 



— (On the) experienced by a fluid in turbulent motion. 582. 

 Respiration (A method of simultaneously studying the adsorption of O2 and 



the discharge of C O. in). 408. 

 Rhythmisation (On subjective). 462. 

 Ringer (W. E.), E. Smits and H. Zwaardemaker. Is caesium radio-active? 



575. 

 Ringing experiments with variegated branches. 756. 

 Rocks (On the) of Doormantop in Central New Guinea. 191. 

 Röntgen-Rays (On the diffraction of) in liquids. II. 112. 

 Rotation (The influence of) on the sensitiveness and the accuracy of a 



pressure balance. 805. 

 RoTT (Sur quelques nouveaux insectes des lignites oligocènes (Aquitanien) 



de), Siebengebirge (Rhénanie). 605. 

 Rubbersol (The electro-viscous effect in). 43. 

 RuTTEN (L.). Geological data derived from the region of the "Bird's head" 



of New-Guinea. 274. 



— and I. Swemle. New findings of pliocene and pleistocene mammals in 

 Noord Brabant, and their geological significance. 199. 



Schaak E (G.). The complex of the conies which cut five given straight 

 lines. 513. 



