472 SCIENCE PROGRESS. 



are either mica or hornblende in different examples, scapo- 

 lite, calcite, a titaniferous garnet, and zircon, with sometimes 

 sodalite, the last occurring in places in large masses. In 

 the latter veins of orthoclase occur with the relations of a 

 secondary product (18). The rock contains a variety of 

 hornblende with very low axial angle. This yielded on 

 analysis only 34 per cent, of silica, while the alkalies 

 amounted to 5^ per cent. 



Rocks of this class are now known from a number of 

 localities in Canada and the north-eastern United States, 

 including Montreal, where the rocks are proved to be of 

 Silurian age, Litchfield in Maine, Salem and Marblehead 

 in Massachusetts, Beemerville in New Jersey, and Red 

 Hill in New Hampshire. Special interest attaches to the 

 numerous dykes within this large region, which are either 

 known or inferred to stand in genetic relationship with the 

 elseolite syenites. These rocks include on the one hand the 

 highly felspathic type bostonite, and on the other hand the 

 complementary products of differentiation represented by 

 camptonite, monchiquite, ouachitite, fourchite, and other 

 peculiar lamprophyric rocks. Rosenbusch founded his 

 type camptonite on Hawes' rock from Campton Falls in 

 New Hampshire. Other examples have been described by 

 Harrington from Montreal, by Kemp and Marsters from 

 the Forest of Dean in New York State, the Hudson River 

 highlands, Whitehall also in New York, etc. From Andro 

 scoggin County, Maine, Merrill (19) has described rocks 

 which might be termed augite-camptonites, containing that 

 mineral both in phenocrysts and in the ground-mass, as 

 well as hornblende, but showing a tendency towards the 

 ophitic structure which places them in an intermediate 

 position between the lamprophyres and the diabases. 



The elseolite-syenite of Beemerville was first recognised 

 as such by Emerson, but Kemp (20) has added consider- 

 able information relative to its modifications and its atten- 

 dant dykes. A porphyritic marginal facies of the main 

 mass is of special interest since Brogger has taken it as 

 the type of his sussexite, the basic end-member of his 

 grorudite-solvsbergite-tinguaite series. It contains 45 per 



