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POPULAR SCIENCE REVIEW. 
for while the intrusive granites are orthoclasic, or, as in Down, sometimes 
albitic (and, let it be remembered, albite is as highly silicated as orthoc-lase), 
and the uncrystallised feldspathic paste is always highly silicated, the 
granitoid rocks on the other hand contain, notwithstanding the presence of 
free quartz, a large proportion of basic feldspars, of which oligoclase is the 
most recognisable, and the feldspathic paste is basic also, approaching oli- 
goclase or anorthosite in composition. — Vide Geological Magazine^ Nov. 
A new Tei'minology . — In a paper on brecciated formations, in the Geolo- 
gical Magazine for November, Mr. John Iluskin defines the several terms 
which he considers it necessary to employ in describing these structures. 
We do not know what physical geologists will think of Mr. Euskin’s 
employment in a new sense of very old and well-understood expressions, 
but for the benefit of those of our readers who may be interested in this 
particular branch, we transcribe Mr. Euskin’s definitions. 1. Supposing 
cavities in rocks are produced by any accident, or by original structure 
(as hollows left by gas in lava), and afterwards filled by the slow in- 
troduction of a substance which forms an element of the rock in which 
the cavities are formed, and is finally present, in the cavities, in pro- 
portion to its greater or less abundance in the rock ; I call the process 
^ secretion.’ 2. But if the cavities are filled with a substance not present (or 
not in sufficient quantity present) in the surrounding rock, and therefore 
necessarily brought into them from a distance, I call the process, if slow, 
‘infiltration;’ if violent, ‘injection.’ It is evident that water percolating 
a rock may carry a substance, present in the mass of it, by infiltration, into 
the cavities, and so imitate the process of secretion. But there are structural 
differences in the aspect of the two conditions hereafter to be noticed. The 
existence of permanent moisture is however to be admitted among condi- 
tions of secretion ; but not of fluent moisture, introducing foreign elements. 
3. If a crystalline or agatescent mass is formed by addition of successive 
coats, I call the process ‘ accretion.’ 4. But if the crystalline or agatescent 
mass separates itself out of another solid mass, as an imbedded crystal, or 
nodule, and then, within its substance, divides itself into coats, I call the 
process ‘ concretion.’ The orbicular granite of Elba is the simplest instance 
I can refer to of such manifest action ; but all crystals, scattered equally 
through a solid enclosing paste, I shall call ‘ concrete ’ crystals, as opposed 
to those which are constructed in freedom out of a liquid or vapour in 
cavities of rocks, and which I shall call ‘ accrete.’ ” 
An Eocene Shore-Crah. — A species of shore-crab, recently discovered in 
the Eocene beds of Hampshire, has been described by Mr. Henry Woodward 
under the title of Goniocypoila Edivardsii, the specific name being given in 
compliment to M. Alphonse Milne Edwards, to whom crustaceous palae- 
ontology is so much indebted. The specimen may be seen at the British 
Museum. It is about eight lines long, and is embedded in a piece of sand- 
stone, the dorsal portion being alone exposed. Like all shore-crabs, the 
carapace is much swollen, especially in the branchial region. — Vide Geologi- 
cal Magazine, Dec. 
The Amiens Gravel. — In a valuable paper, read before the Geological 
Society, at its meeting November 7, by Mr. A. Tyler, the following 
conclusions were based upon the evidence adduced by the author : 
