1 84 The American Geologist. ^^''^''^' ^^oi. 
Brachiopoda, though he lays a strong emphasis on the distinction be- 
tween the "Ecardines" and "Testicardines" (=Inarticulata and Articu- 
lata.) G. F. M. 
Kleine paleontologische Mittlieihmgen. von Dr. F. Huene in Tubingen, 
mit 2 Taf. (Neu Jarb. fitr Mineralogie &c, 1901, Bd. i, s. 1-8.) 
In this article Baron v. Huene describes a new species of Medusa 
(Medusina geryonides) from the Murchisonia slate of Wiesenteig in 
Wurtemburg of which the preserved impression exceeds an inch in 
diameter and is quite distinct and characteristic. 
He also gives figures and a descripion of a new Cycad (Zamites 
infraooliticus) from the Blagdini zone near Langenbruck in Switzer- 
land. The oroginal of this species is in the museum of Lausanne. 
G. F. M. 
Action of Ammonium Chloride upon Analcite and Leiicite. By F. W. 
Clark and Steiger. {Am. J. Sci., 159, 1 17-124.) 
The article records the results of an investigation on the action of 
ammonium chloride upon the minerals analcite and leucite when the 
latter are heated separately with this reagent in sealed tubes at 35o°C ; 
also the meaning which the results obtained have in regard to the 
chemical constitution of the two minerals. Both minerals suffer a 
substitution of their alkali by ammonium, yielding the same compound 
whose composition is that of an ammonium leucite, NHiAlSi^Oe. This 
fact is believed to indicate an original similarity in the two minerals 
^v*hich is also borne out by crystallographic and other resemblances. 
A further study of the chemical properties of the ammonium derivative 
leads the authors to think that analcite and leucite are not true metasili- 
cates but either salts of a polymeric metasilicic acid or a mixture of 
ortho and tri-silicates. c. H. w. 
Chemical Study of the Glaucophane Schists. By H. S. Washington. 
(Am. J. Sci., 161, 31-59.) 
A consideration of the chemical and mineralogical composition of 
the above class of metamorphic rock as shown by a series of admirable 
chemical analyses of specimens from some seven localities, leads to 
conclusions concerning their classification and origin which are briefly 
and concisely given by Dr. Washington in his summary as follows: 
"The Glaucophane schists belong to two main groups, sharply sepa- 
rated from each other. The larger one is basic, composed chiefly of 
glaucophane and epidote, often with abundant garnet, zoisite, diallage, 
and sometimes smaller amounts of mica, feldspar and quartz, and rutile 
and titanite as frequent accessories. Chemically these closely resemble 
the composition of the rocks of the gabbro family, and are apparently 
divisible into two sub-groups, one high in CaO, the other low in it. 
These are in most cases almost undoubtedl}' derived from such 
igneous rocks or their tuffs, but also possibly in rarer cases from 
sediments or slates of similar composition. These basic glaucophane 
schists scarcely differ in composition from the amphibolites and 
eclogites, and the difference in their formation is probably to be 
ascribed to differences in the conditions of metamorphism. A smaller 
