we 
Geology and Natural History. 65 
Mr. Harrington inclines to the conclusion that the mineral is a 
hydrous carbonate of alumina, lime and soda; and that it is 
related therefore to hovite, which the Messrs. Gladstone made a 
carbonate of alumina and lime. Its crystalline character and its 
uniformity in optical and chemical characters show that it is not a 
mechanical mixture. 
13, Tables for the Determination of Minerals, by their Physical 
properties, ascertainable by the aid of such simple instruments as 
every student in the field should have with him. Translated from 
the German of Weissacu. Enlarged, and furnished with chemi- 
tions of three New Species, and a Jew Supplemental Remarks on 
y wn Scorr, Curator of 
Society, was read in Feb., 1870. It is illustrated by 18 plates, 
eleven of which relate to the structure of the stem, ete., a sub- 
Ject which is here treated with freshness and ability, as well as 
tersely, and to which interest is added by some ingenious specula- 
origi ing summary, ¢ 
terior to the periphery, not a few of the tree-ferns have very simi- 
lar characteristics. “In both, diametrically and longitudinally, 
Stowth is strictly apical; in both the stems are limited in their 
diametrica] growth, and from the first traces of their formation 
the axial and peripheral developments are simultaneous; and as 
Seon as the normal thickness has been attained, all further peri- 
heral mcrease ceases, and the axis grows upward iv a cylindrical 
rm. In Palms the growing point is conical, and in tree-ferns 
terminally flattened ; so that in the one case the nascent vascular 
bundles are almost horizontally arranged at the apex, in the other 
they are from the beginning vertical; but in both all cellular in- 
“rease of the body of the axis has ceased ere the fronds have 
AM. Jour. Scr.—Tairp = Vou. IX, No. 49 —Jan., 1875. 
