phync manner through the whole. Hypersthene is present 

 also in the rock, but does not include pleonaste. Olivine 

 is absent. (See fig. 9). 



Prom a chemical point of view the occunvinv , ,f pk< ><iast.> 

 associated with monoclinic pyroxene is a reversal of the 

 normal order of chemical affinities for the alumina has 

 entered into combination with magnesia and ferrous oxide, 

 leaving the lime to enter pyroxene. The very pale colour 

 of the pyroxenes, especially when these are most abundant, 

 indicate that for rocks of this basicity the ratio of magnesia 

 to iron is abnormally high, and that ferric iron is unusually 

 low. It is here suggested that these rocks ivsult from an 

 admixture of peridotitic magma with the partially crystal- 

 lised differentiation products of a gabbroid magma, or by 

 resorption of felspar by the still molten olivine in a crystal- 

 lising felspar-olivine magma. By the solution of felspar in 

 the peridotitic magma those irregular spaces are formed in 

 which the syntectic melt crystallises. By reactions in the 



