96 TERTIARY LAND ROUTES r.KTWEEK AMERICA AND AFRICA. 



Finally^ in 1910,* Dr. Osbcrn abandoned as a matter of im- 

 perfect record the theory of an Antarctic land connection even 

 between South America and Au.straha. 



He now believes that the greater part of the animals and 

 plants of the .Southern Continent are of northern origin, and that 

 the evidence advanced for Antarctic coimection> is probably ex- 

 plainable through distribution from the north. 



Of the South American mammals. Dr. Osborn remarks, f 

 " There is no satisfactory evidence of connection at any time with 

 the manmialian life of Africa except in the very late Pliocene 

 times, through migration by way of North America." 



It was a delight to find that these conclusions of Dr. Osborn, 

 reached from a study of the vertebrates, should so harmonize 

 with my own, based on the invertebrates. 



In conclusion, we may say that our present knowledge indi- 

 cates: (i) that the early Tertiary molluscan and mammalian 

 faunas of South America were closely akin to those of North 

 America; and (2) that the evidence furnished by Ix)th the mol- 

 luscs and land vertebrates of South America is against the ex- 

 istence of Tertiarv or Cretaceous land bridges to Africa. 



TRANSACTIONS OF SOCfETIES. 



Royal Society of South Africa. — Wednesday, October 15th : Dr. L. 

 Peringuey, F.E.S.. F.Z.S., Presideni. in the ciiair. — " A new mimicry plant 

 {Mesembriaiithcuiiim lapidcfonne)" : Prof. R. Marloth. In summer the 

 plant consists only of two fleshy bodies (the leaves), which are half buried 

 in the sand. Each leaf is shaped like a tetrahedron, with blunt edges and 

 \angles, and brownish-red in colour ilke the angular fragments of stone 

 among which the plant grows. It is consequently most difficult to detect 

 even in localities where its occurrence is known. In spring the plant pro- 

 duces two flowers, one at each side, which are joined to the parent plant 

 by a very thin connection. The ripe seed vessel is consequently easily 

 detached at this spot and can be carried away b}' the wind — a mode of 

 dispersal unique among the nearly 400 species of the genus Meseuihrianthe- 

 muni. " On an experimental modification of Van der Waal's equation " : 

 J. P. Dalton. The a of Van der Waals's equation is considered to be a 

 function of the temperature only, and the b to I)e independent of the 

 temperature. The function is then determined for a typical normal sub- 

 stance (isopentane) from the experimental isothermals. The modified 

 vapour pressure curve is found to represeint experimental results for both 

 normal and abnormal substances much more closely than the original. 

 The new values agree well with the Van derWaals vapour pressure for- 

 mula, and the modified equation is used with quite satisfactory results for 

 the calculation of latent heats and also for oi)taining the curve of inversiion 

 of the specific heat of saturated vapours. — " Barometric variability at Kim- 

 berley and elsewhere " : Dr. J. R. Sutton An attempt to determine work- 

 ing constants which shall represent the " cyclonic activity '" at various 

 places in South Africa and such other places outside as have available 

 information regarding the barometer. Tables are given showing the 

 monthly mean constants, with maximum and minimum values, or baro- 

 metric variability. One deduction is that the " equinoctial gales." so far 

 as barometric changes can represent them, have no existence in fact. 



* " The Age of Mammals," p. 

 t Op. Cit. p 78. 



