112 The Irish Naturalist. 



March 20th.— Mr. J. Stewart delivered an interesting address de- 

 scriptive of ants, their habits, varieties, and distribution, illustrating the 

 subject by means of some very beautifully-coloured diagrams and lantern 

 transparencies, also living specimens from this neighbourhood. 



ROYAE DUBEIN SOCIETY. 



February 21st. — A paper upon Kozoonal Structure in the limestone 

 rock of Monte Somma, by Dr. J. W. Gregory, F.G.S., and Prof. H. 

 Johnston-La vis, FG.S., was communicated by Prof. Cole. The authors 

 show that the limestone blocks ofMesozoicage in Monte Somma (Vesuvius) 

 have frequently become metamorphosed into crystalline masses consis- 

 ting of alternating bands of calcite and various silicates. The authors 

 regard the silica, magnesia, &c, as derived from the igneous rock, by 

 chemical interpenetration and interaction. Where the silicate, as often 

 happens, is olivine (montecellite), or a pyroxene, a complete simulation 

 of the structure of the supposed foraminifer Eozoon canadenseis produced ; 

 the layers of silicates occur parallel to the surfaces of any igneous vein 

 that may have intruded into the limestone, and they become closer to 

 one another in the areas farther removed from contact. The " proper 

 wall," the "stolons," and in places the " canal-system " of Eozoon are 

 recognisable under the microscope ; and the authors adduce evidence to 

 show that the typical Eozoonal limestone of Canada may have arisen 

 similarly as a product of contact-metamorphism. 



Prof. GrenvieeE A. J. CoeE, M.R.I.A., F.G.S., read apaper on Derived 

 Crystals in Basaltic Andesite of Glasdrumman Port, Co. Down. A large 

 composite dyke shows at this point a band of andesite on each side, from 

 4 to 17 feet wide, and a more recent dyke of eurite in the centre, 36 feet 

 across. The eurite includes numerous blocks of andesite, and sends off 

 veins into it; but the pyroxene and glass of the latter rock have become 

 remelted at the contact, a delicate interpenetration of the two magmas 

 has occurred, and the porphyritic crystals of quartz and pink felspar 

 from the eurite are found completely surrounded by the dark andesite. 

 Thus a pre-existing rock comes to include crystals derived from one that 

 has subsequently invaded it, and hand-specimens, apart from study in 

 the field, would be of a most misleading character. 



NOTES 



BOTANY. 



PHANEROGAMS. 



Artemisia Stelleriana in Ireland.— Mr. Colgan follows up Prof. 

 Areschoug's article in the March number of the Journal of Botany on the 

 position of Artemisia Stelleriana in the European flora, by an examination 

 of its claim to a place in the Irish flora, written in his usual careful style, 

 and published in the April number of the same journal. Mr. Colgan's 

 conclusion is that there can be no doubt that this plant is an introduc- 

 tion in its habitat on the North Bull. It appears that the plant was 

 cultivated for many years at St. Anne's, and that the refuse from the 

 garden there was shot on the foreshore within half-a-mile of where the 

 plant now grows. Given a westerly wind and a rising tide, a few scraps 

 of the Artemisia have floated across the narrow channel to the North 

 Bull, and, as the plant is a particularly hardy and free-growing species, 

 the mystery of its appearance is solved. 



