1892.] NEW YORK ACADEMY OF SCIENCES. 69 



ciated with elaeolite-syenite. This is true of the localities in the 

 Monchiqiie Moimtaiiis of Portugal, of the Norwegian exposures, 

 of those in Brazil, at Montreal, Mag-net Cove, Salem (as recentlv 

 discovered by J. E. Woltf), and Beeraerville, and it is possible 

 that they may yet be found in the other American localities. The 

 dikes lying outside the syenite areas in Arkansas have been re- 

 cently described by the writer, and in the paper which has just 

 appeared in the annual report of the Arkansas State Survey for 

 1890, vol. ii, p. .392, a review is given of those elsewhere. Along 

 the eastern side of the Beemerville syenite a number of such out- 

 breaks are found. Their determination as porphyrite in the Ameri- 

 can Journal of Science for 1888 has since been revised. Althoug-h 

 the avaihible material is much decomposed, they were shown to 

 consist of large biotite phenocrysts with somewhat smaller and less 

 abundant augite, in a groundmass mostly changed to calcite, but 

 which was thought to have had close affinities with nepheline. 

 Some plagioclase also appeared as a constituent of the groundmass. 

 The rocks are dense and black and belong in the Lamprophyre divi- 

 sion. In the Arkansas examples much fresher material was af- 

 forded, and this, too, from about 75 or 100 dikes. There is almost 

 no definite nepheline, l)ut the minerals are in a glass of no great 

 abundance. It is probable that tliis was the original condition of 

 these basic dikes at Beemerville. The Arkansas dikes, rich in bio- 

 tite (and in instances this forms half the rock), were named ouachi- 

 tite, from the Ouachita River, along which they occur. Macro- 

 scopically, the ouachitite is indistinguishable from the alnoite of 

 Tbrnebohm (cited from the original Swedish by Rosenbusch, Mass. 

 Gest., p. 804), the Norwegian melilite rock, but they contain ho 

 trace of melilite. 



The New Jersey rocks are mostly ouachitite, with some four- 

 chite, and the names are accepted from the later developed locality 

 on account of the fresher material. 



There is some underlying genetic connection between the elaeo- 

 lite-syenite and these other basic rocks, but what it is I feel at a 

 loss to say. Rosenbusch thinks them due to a splitting of his foy- 

 aite magma. Other dikes occur at a distance of ten or fifteen miles; 

 a number are shown in the map, A. J. S., Aug. 1889, p. 131. The 

 one called mica-dialiase by Emerson, from Franklin Furnace, has 

 long been known, and others of the same sort have recently been 

 determined by G. H. Williams for F. L. Nason, in the last annual 

 Report of the New Jersey Survey. Rosenbusch, however, says in 

 a recent letter to me, regarding some specimens sent him of the 

 Franklin Furnace dike, that there is nothing of the true ojjhitic 

 structure of diabase in them, but that they are a lamprophyre of 

 unusual type, and near the caraptonites. My own observations 

 would substantiate this view. 



I have also a curious dike from Hamburg, north of Franklin 

 Furnace, that is not yet mentioned in print and that is closely re- 

 lated to the theralites." It cuts blue limestone and has some curious 



