240 Geological Society, 



Of four others : — 



Transpiration time. Boiling-point. 



o 



Formic ether 0*51 1 55*5 



Acetic ether 0*553 74*0 



Butyric ether 0*750 



Valerianic ether 0*827 133*5 



Judging from these last observations, the order of succession of in- 

 dividual substances in any natural series will be indicated by the in- 

 dividual transpirability of these substances, as clearly as it is by their 

 comparative volatility. Transpiration and boiling-point observations 

 may come thus to claim an equal interest. In carrying out the in- 

 quiry, it will probably be found advantageous to transpire the liquids 

 at a fixed temperature which is somewhat elevated. A large number 

 of substances are liquid at 100° C, of which the transpiration times 

 could easily be obtained. Slow transpiration and low volatility ap- 

 pear to go together, and both to be connected in a general way with 

 a heavy molecule. So also the annexation of constitutional water to 

 the hydrated acids and alcohols appears to impede the transpiration 

 of these substances. 



GEOLOGICAL SOCIETY. 



[Continued from p. 166.] 

 June 4, 1862. — Prof. A. C. Ramsay, President, in the Chair. 



The following communications were read : — 



1. " On the disputed affinities of the Purbeck Mammalian genus 

 Plagiaulax:' By Hugh Falconer, M.D., F.R.S., F.G.S. 



The author first referred to his former description (in the Journal 

 of the Society, vol. xiii. p. 261, &c.) of Plagiaulax as a rodent form 

 of Marsupial, having affinities with the existing Hypsiprymnus ; and 

 then he drew attention to the very different opinion of its relation- 

 ship expressed by Professor Owen in the article " Palaeontology " in 

 the 8th edition of the ' Encyclopaedia Britannica,' and in the reprint 

 of that article as a separate work, where it is said to have been " a 

 Carnivorous Marsupial." 



Dr. Falconer then reviewed the dental characters of Plagiaulax in 

 detail. Of the incisors he said that, in regard of number, order of 

 suppression, collateral position, and relation to the premolars, they 

 correspond exactly with the type of Marsupial herbivora, and are 

 wholly at variance with the carnivorous type ; and he argued that 

 Professor Owen's argument drawn from Thylacoleo has no bearing on 

 the incisors of Plagiaulax, and gives no support to the carnivorous 

 inference. Of the premolars, after a full comparative re-examina- 

 tion, Dr. Falconer stated that, in agreement with his already pub- 

 lished views, he finds reason to regard the carnivorous deduction 

 from the shape of the premolars to be untenable. 



The form of the lower jaw of Plagiaulax having been regarded by 

 Professor Owen as conforming with the carnivorous type, the author 



