1897] NOTES AND COMMENTS 15 



within the ovary cavity, namely in Baeckca diosmifolia (a member 

 of the myrtle family). Certain ovaries of quite normal external 

 appearance contained numerous perfect or sometimes imperfect 

 stamens, but no trace of any ovules. 



Some Basic Dyke-kocks from Southern India 



A recent issue of the Records of the Geological Survey of India 

 (vol. xxx. part i.) contains a paper by Mr T. H. Holland dealing 

 with certain basic dykes widely distributed in Peninsular India. 

 On both geological and petrographical grounds they are correlated 

 with the Cuddapah lava-flows, and they shew none of the effects 

 of dynamic metamorphism so general in the older series of dykes 

 referred to in the Dharwar system. The author treats the rocks 

 under three groups : olivine-norite, augite-norite, and augite-diorite. 

 The first consists essentially of olivine, enstatite, augite, and a basic 

 plagioclase, with subordinate biotite. The second lacks olivine, and 

 has more augite relatively to enstatite. In the third group biotite 

 and usually enstatite have disappeared, a comparatively late crys- 

 tallization of augite gives a tendency to the ophitic structure, and 

 interstitial micropegmatite (sometimes with potash-felspar) is invari- 

 ably present. Considerable variations occur, including transitions 

 in the first group to peridotites and in the second to pyroxene-rocks. 

 To each group there are ' hemicrystalline ' equivalents corresponding 

 with the rocks of plutonic habitus, and some of these present types 

 not hitherto described but comparable with the limburgites or 

 magma-basalts. These contain phenocrysts of olivine, of enstatite, 

 or of both minerals in a dark compact matrix, largely of glass. The 

 author also points out resemblances between the dyke-rocks and the 

 Cuddapah lavas of which they are the probable equivalents. 



The rocks styled augite-diorites seem to be practically identical 

 with some which in this country have been termed quartz-bearing 

 gabbros, etc., and the author makes an interesting comparison 

 between the Indian examples and those of Carrock Fell, St David's 

 Head, and Carlingford, with the well-known rocks of Penmaenmawr 

 and the Whin Sill. He finds no evidence to support Professor 

 Sollas' suggestion that the micropegmatite in such rocks is the result 

 of a later injection of a distinct acid magma into minute veins and 

 druses. He regards it as the final product of crystallization of the 

 rock formed under somewhat changed (' aqueo-igneous ') conditions, 

 consequent upon the concentration of the original water in the 

 residual magma. He suggests that distinct veins of granophyre 

 traversing the rock, as described by Sollas in thfe Carlingford dis- 

 trict, may be ' contemporaneous veins ' rather than later injections, 



