1897,] Paleontology. 1053 
One of the most interesting rocks of the district is the Bassick Mine 
agglomerate made up of fragments of many different rocks cemented 
by fine debris of the same character. This is now usually so much de- 
composed that its original constituents can in many cases no longer he 
recognized, 
In addition to the voleanic rocks mentioned above, a mica-dacite 
and a limburgite were observed. They are, however, quite rare, All 
the volcanic rocks have been decomposed by solfataric action, yielding 
products of various kinds, the two most important of which area white 
siliceous clay resulting from the alteration of pitchstone and a quartz 
alunite rock produced from rhyolite, Analyses of the pitchstone and 
its alteration product follow: 
SiOz AlO; FeO; FeO = CaO MgO K:O Na,O H:O Total 
Pitehstone 71.56 13.10 .66 .28 .16 .ī4 .14 4.06 3,77 5.52= 99.99 
Clay 71.71 12.36 1.10 pa 111 1.21 36 .17 11.97 = 100.16 
The andesite is often muscovitized, all of its constituents but augite and 
orthoclase passing over into aggregates of muscovite apparently with 
great ease. 
The report closes with a discussion of differentiation in which the 
author does not reach any definite conclusions, except that in the case 
of the Rosita rocks much of the differentiation which resulted in the 
different phases of the various types must have taken place either after 
the lavas had reached their present position, or at any rate at no great 
depth under the surface. 
Notes.— Wolff! gives a description and a map of the exposures of 
eruptive rocks occurring in Sussex Co., N. Y. These exposures in- 
clude those of the well known eleolite-syenite and associated dyke 
rocks at Beemerville. 
oe 
PAL ONTOLOGY. 
Schuchert’s Synopsis of American Fossil Brachiopoda.’ 
—Students of Brachiopoda, as well as Mr. Schuchert, are to be con- 
gratulated upon the publication of this important work. Its prepara- 
tion has extended over a period of eleven years, and entailed references 
' Ann. Rep. State Geol. of New «agente 1896, p. 91. 
2 A Synopsis of American Fossil Brachiopoda, including Bibliography 
Synonymy. By Serene Bulletin U. 8. Geol, Survey, No. 87. 
