60 GEOLOGICAL MEMOIRS. 
especially where, on the one hand, they are still mixed with felspar, 
or on the other, where they occur in undoubted sedimentary strata 
full of petrifactions, and often assuredly secreted through the imstru- 
mentality of water. It is certainly of very great importance to collect 
more observations on this subject. 
Many interesting notices are given regarding amygdaloids and 
agate masses, especially regarding the relation between proper amyg- 
daloids, geodes, and the masses filled with similar mimerals, and 
regarding the quartz and agate masses in the felspar porphyries of 
Saxony. 
Tip iting of reticulated laminze in the balls of sphzerosiderite 
(septarize) are highly interesting, but might easily be imereased, as 
these nodules are so very common and are collected for use on so 
large a scale. 
Veins in marble present in miniature all the phenomena of veins, 
though they may owe their substance solely to the neighbouring 
rock. They are im every respect similar to the quartz ves in the 
flmty slate (Lydian stone), with which the masses of quartz in the 
porphyry mined at Altenberg has so much similarity. 
The fibrous laminz, as those of fibrous limestone in the caleareous 
clay-slate of Moutiers, of fibrous gypsum in the gypseous clays and 
schistose marls of all formations, are explained in a simple manner - 
from the similar layers of ice formed in a mass of frozen earth. 
The incrustations and laminze of calc-spar, gypsum, iron pyrites, 
&c., im fissures of coal, illustrated by examples from Plauen and the 
vicinity of Zwickau, are not less important than the nests of veins 
and laminze in the old secondary limestones. 
[J. N.] 
The TreBicu Grotto, near Trieste. By A. von Mortor. 
[From ‘ Berichte iiber die Mittheil. v. Freunden d. Naturwis. in Wien von 
W. Haidinger,’ vol. iii. p. 380.] 
THE maritime districts of Illyria show only two geological forma- 
tions ; the one sandstone and slate, which is properly nothing more 
than the Vienna sandstone ; the other, the so-called Karst, resting on 
this in extensive but isolated beds. The Karst formation, consisting 
especially of white and rather pure limestone, is not only washed-out, 
furrowed, and pierced with holes in many places, but the whole rock 
is so traversed, and, as it were, sown over with deep funnel-shaped 
and crateriform abysses, that the mass of strata, 1000 feet thick, is 
truly described as being fuller of pores than a sponge. Hence the 
rain speedily smks into the intericr of the mountain, and the only 
water seen on the surface is at most a few small pools, nowhere the 
most trifling streamlet. In the region of the sandstone and slate, on 
the contrary, running water, both in brooks and rivers, is not wanting ; 
but whenever they reach the limestone formation they run into it, 
often through highly romantic, portico-like openings, and continue 
their course below ground, only returning to the light where the 
sandstone again appears. In heavy storms of rain the water accu- 
