290 NATURAL SCIENCE [November 1898 



subject synthetically ; he has shown that the structure of the world 

 can be explained by subsidences in the crust, when subterranean 

 support is removed by the shrinkage of the internal nucleus, and 

 by the movements of elevation which produce the chains of fold- 

 mountains. Suess's view explains the structure of the continents 

 and ocean basins, but not their arrangement. To settle this problem 

 fuller knowledge is needed as to the distribution of land and water 

 in past times. Neumayr's attempt to settle this question for the 

 Jurassic was premature, and his conclusions are untenable. We are 

 thus still dependent upon the deductive systems for suggestions as 

 to the most profitable lines of research. Elie de Beaumont's famous 

 scheme attached undue importance to linear symmetry and was too 

 artificial. It led, however, to the tetrahedral theory of Lowthian 

 Green, which regards the world, not as shaped like a simple tetra- 

 hedron, but as a spheroid slightly flattened on four faces. Such 

 fiattenings occur on hollow, spherical shells, when they are deformed 

 by uniformly distributed external pressure. The oceans would 

 occupy the four depressions thus produced, while the land masses 

 occur at the angles and along the edges. The existing geographical 

 arrangement is in general agreement with this scheme ; for as the 

 tetrahedron is hemihedral the assumption that the lithosphere is 

 tetrahedral explains the antipodal position of land and water, the 

 excess of water in the southern hemisphere, and the southward 

 tapering of the land masses. The main lines of the existing system 

 of fold-mountains have a general agreement with the arrangement 

 of the edges of a tetrahedron. Some striking deviations occur, but 

 are explicable by the variations in the composition of the litho- 

 sphere, and the existence of impassive blocks of old strata which 

 have moulded the latter movements. The lines of the old fold- 

 mountains of the Hercynian system may have been tetrahedrally 

 arranged, but with the axes occupying different positions from those 

 of the great Cainozoic mountain system. So far, however, there is 

 no completely satisfactory theory of geomorphology, for which we 

 must wait for further information as to the distribution of land and 

 water in successive epochs of the world's history. For the historical 

 method promises more reliable results than the deductive method." 



Toxodon 



The important serial publications of the Museum of La Plata, Argen- 

 tina, contain some of the most valuable contributions to natural 

 science which have been made during the last decade. We have 

 had frequent occasion to refer to them, and to the vast store of 

 unique specimens which the energy and genius of Dr F. P. Moreno 

 have accumulated in the comparatively new capital of the State of 

 Buenos Aires. The Revista and Anales, however, contain only 



