DUBLIN MICROSCOPICAL CLUB. 439 



occurs iu grains filling eavities and small fissures in the rock. 

 It is black, glossy, and has a conchoidal fracture, resembling 

 pitchstone, but the chemical analysis shows it has no connection 

 with this mineral, as it belongs to the ferrugino-chloritic group. 

 "With a 2-inch object glass it appears translucent, of a rich 

 brownisb yellow to bronze colour, sometimes traversed by dark 

 prism-like bars. It is structureless or reticulated, filling cavities 

 and the narrow fissures between the other minerals, which con- 

 sist chiefly of unaltered olivine-plagioclase, a little augite, and a 

 few grains of titano-ferrite. The mineral does not polarise, but 

 with a higher power (1-inch objective) shows evidences of a reui- 

 form structure. The olivine in the rock is unusually fresh and 

 polarises vividly. 



Section of Spine of Salmacis rarissima, Agassiz. — Mr. Mackin- 

 tosh exhibited a cross-section oi Salmacis mrissima, Agassiz, one 

 of the Acanthopneustes group, which though apparently mono- 

 cycliue in its mode of growth is not truly so, inasmuch as the 

 solid wedges which make up the greater part of the spine exhibit 

 a series of expansions at regular intervals indicating periods of 

 growth. 



Macro- and Microspores of Isoetes Morel, lsloove,exhil>ited. — Dr. 

 David Moore showed specimens o£ the macro- and microspores of 

 his new species, Isoetes Morei, just described and figured iu the 

 ' Journal of Botany,' and contrasted the latter with those of the 

 allied species Isoetes setacea, a native of the Mediterranean 

 district. 



December IQth, 1878. 



Neomeris, undescribed species, shown. — Dr. E. Perceval Wright 

 exhibited mounted specimens of a species of the genus Neomeris, 

 collected in the Priendly Isles, by the late Professor Harvey. In 

 the working collection of Dr. Harvey tlie species stood recorded 

 under the manuscript name of N. capitata ; from iV". dumetosa of 

 Lamarck it ditfered in very many respects, and from N. {Decais- 

 nella) nitida of Harvey it diflered, not only iu being less calca- 

 reous, but in the beautiful regular hexagonal shape of the cells, 

 and by the apparently one-celled stipes. 



Section of Quartziferous Diorite of Quenast, sJiown. — Professor 

 Hall, P.E.S., exhibited a section of quartziferous diorite of 

 Quenast, kindly lent him by M. I'Abbe Keynard. In the crystal- 

 line grains of the silica weye to be seen, by the aid o£ a high 

 magnifying power (800 diameters), fluid cavities containing 

 minute translucent cubes, inferred to be those of sodium chloride 

 (or common salt), and aboi;t toioo*^ of an inch in size. In one 

 of the cells exhibited the vacuum bubble was observed close 

 beside the crystal. The " diorite quartzifere " of Quenast is 

 remarkable for containing these cubes, which have been also 

 observed by Dr. Zirkel in the granite of Arran, in Scotland, and 

 in other rocks. 



