and is almost compact in texture. It is green in colour and contains 

 epidote in veins and radial groups. The hornblende is described as fibrous 

 (schiltig oder faserig). This raises the presumption that the rock is not a 

 true diorite, but an epidiorite. 



Some very remarkable rocks which may be referred to in this 

 connection occur at Carrigmore, Co. Wicklow. The following description is 

 based on specimens in the ALLPORT collection in the British Museum. One 

 section shows large opbitic plates of an intensely dichroic biotite, with 

 numerous inclusions of apatite, a pale coloured pyroxene with brownish 

 inclusions parallel to the ortho-pinacoidand basal plane (pseudo-hypersthene) 

 aggregates of water-clear plagioclase (compare Fig. 1, Plate VIII.) with 

 green infiltration products along cracks and the boundaries of the indivi- 

 dual grains, greenish fibrous pseudomorphs which may represent enstatite 

 and a few grains of opaque iron-ore. The pyroxene individuals are often 

 twinned parallel to 100, and when this is the case the characteristic 

 herring-bone lineation, due to inclusions parallel to 001, is seen in sections 

 more or less parallel to 010. 



The section of another rock from the same locality is still more 

 remarkable. This section consists of biotite, a monoclinic pyroxene, 

 plagioclase, apatite, and magnetite, exhibiting the same characters and 

 relations to each other as in the above ; but it contains in addition large 

 grains of olivine and smaller grains of a feebly but distinctly pleochroic 

 pyroxene. The olivine in some cases contains parallel rows of inclusions 

 and irregular cracks along which there has been a great deposition of 

 magnetite ; indeed most of the magnetite in the rock is present in the 

 olivine. The substance of the olivine is perfectly fresh. The pleochroic 

 pyroxene is also fresh and contains no inclusions; unfortunately the 

 grains are so irregular and the cleavages so faintly indicated that it is 

 impossible to determine the system of crystallization. The pleochroism 

 (reddish and greenish tints) favour the idea that it is a member of the 

 enstatite group This pyroxene exhibits a decided tendency to form zones 

 round the olivine, reminding one of the zoned olivines described by 

 Mr. ADAMS, from the Saguenay river. There is, however, no actinoiite 

 border outside the border of pyroxene, and in this respect the case is 

 similar to one observed by the author in a gabbro from the Lizard. Those 

 authors who lay stress on the diallagic condition of the pyroxene will of 

 course term these rocks gabbros. 



The basic igneous rocks in the metamorphic districts of the west and 

 north-west of Ireland have not yet received much attention at the hands of 

 modern petrographers. The facts described by Mr. TRAIL in the Explanatory 

 Memoir to accompany sheets 39, 40, 51 and 52 of the Geological Survey of 

 Ireland seem to show that they are of great interest from the point of view 

 of metamorphism. They occur as sheets and dykes in Western Mayo and 

 belong to two periods, pre-Carboniferous and post-Carboniferous (probably 

 Tertiary) Mr. TRAIL says : " There is a general resemblance between the 

 rocks of each of these groups, for they both belong primarily to the 

 pyroxenic division. . , . The older series, to a large extent, 



