360 Scientific Proceedings, Royal DvMin Societ'y. 



Next comes a band near Drumahaire (three miles N.E.), trend- 

 ing nearly east and west. It is probably 300 feet thick at least ; 

 but its extension along the line of strike is not ascertainable, 

 owing to thick coverings of drift and bog. 



Finally, close to Shanavan's Bridge, near Manorhamilton, there 

 is a well-defined band of serpentine, trending nearly N.E. and 

 S.W. It is, however, cut off by two faults, and can only extend 

 about half a mile in each direction. This contains mica and 

 chlorite. 



Neither of these last serpentines are perceptibly magnetic, 

 although not generally different in external appearance from the 

 first. They also want the numerous bands of tremolite which 

 distinguish the former. — (See Part III., p. 368.) 



Rosses Point Section. — In this region a triangular boss of 

 metamorphic rock occurs, which has not yet been noted on any 

 map, or in any other publication. It is about 2| miles long, and 

 about a mile at its greatest width. It is difiicult to account for 

 its appearance here, within the limestone district, unless we 

 suppose it to have been upheaved by more than one fault. One 

 to the north is sufficiently apparent, but the other junctions are 

 hidden by drift. 



The rocks in this district are of a similar character to those of 

 the Ox Mountains, and consist of coarse gneiss, often hornblendic, 

 and mica schist. Quartzites a.re absent. The gneiss contains in 

 places small garnets. 



List of Minerals, and Remarks thereon. 



Quartz. — Disseminated throughout ; sometimes occurs in large 

 ill-defined crystalline masses. 



Felspar. — Chiefiy, if not altogether orthoclase, both white and 

 pink ; the latter very common ; both often in extremely large 

 crystals, as near Colooney, also in the rock north of Ballintogher. 



Mica. — Muscovite and biotite are found very usually in the 

 same rock, often in very large crystals. Some specimens (mus- 

 covite) obtained near Ballintogher afforded flakes more than 

 1| inches in diameter. 



Tourmaline is not unfrequently met with in small crystals. 

 Near Colooney a magnificent mass occurs, consisting of large 

 crystals, radiating in a star-like form, about two feet in 

 diameter. The crystals, which have a tapering form, are some- 



