352 Morris Morris: 



the accessories. The liypeisthene, which is practically confined to 

 the dacite or superficial rock, and even tlien is unstable in the 

 presence of heat, changing over into Ijiotite, is probahly not a true 

 phenocryst, but a crystal of the second generation, resembling, in 

 this respect, the olivine of basalts, ^ which attains such a size owing 

 to its power of spontaneous ci-ystallisati(in, and to its rapid rate of 

 growth. 



Other undifferentiated dykes, viz.. hornblende porphyrite, found 

 by Prof. Skeats (13) near Aura, Ijoth in the granodiorite and in 

 the dacite, are regarded by him as " genetically connected with the 

 granodiorite, and as forming one of the later incidents connected 

 with the plutonic rock." 



The dykes marked on tlie map show indications of a radial 

 -arrangement with reference to some centre in tlie Dandenongs. 

 Further observation of dykes on the south-west and south-east 

 flanks of the Range are needed to be certain about it. 



D. — Thk V^olcanic Succession. 



The following rock analysis have been made through the kindness 

 •of Mr. E. J. Dunn, by the officers of the Geological .Survey 

 Laboratory : — 



