KEVIIOW. 
417 
died in conil-inud impregnated with silicic acid, would tlicy have been pre- 
served ? — Yours, A., Land's Eud. — Mineral-veins cannot, in the sense the 
question is put by our correspondent, be said to be due to sedimentary deposits. 
In some cases they present the appearance of stratification, as iu those 
instances of filled-up cavernous hollows noticed and described iu the papers by 
Dr. Watson, in vols. i. and ii. of this magazine. Mr. Sahnou's articles on ore- 
veins, commenced in oui- last number, will also give oui- correspondents much 
information on this topic. 
Certain bands of ironstone-nodules are interstratified in the sedimentary beds 
of the Inferior Oolite and of the Lias. The Lower Greensand of the Cretaceous 
group, aud the " basemeut-bed" of the London Clay amongst the Tertiary rocks 
otter instances of sedimentary strata being so highly impregnated with mineral 
matter as to be sometimes equivalent in metallic richness to the mineral veius. 
The ironstone-nodules and strata of the Wealds of Kent and Sussex were ui 
llomau aud mcdiajval times largely worked as ores, but mineral-veins proper 
cannot be regarded as contemporaneous formations with the strata in which 
they occur. 
Ehrc'uberg is tlie great authority on Infusoria. A very nice condensed 
account of this class was pubUshed some years since by Mr. Pritchard, the 
optician and microscopist, and a new edition has been more lately produced. 
Dr. Mantell has given an account of some British species in a very interesting 
little volume. The " Mierographical Dictionary" gives a vast amount of in- 
formation about Infusoria ; and there is a good article on the subject in the 
" Cyclopeedia of Anatomy and Physiology." 
It is not in every case, as rightly suggested, that organic objects are pre- 
served ; the circumstances attendant on their fossilization must of course be 
exceptional. 
Fossils of the Red Chalk. — I am able to add one species to the Verte- 
brata in the list of fossils given by Mr. Wiltshire ui his iiiterestuig paper on 
the " Ked Chalk." I found a tooth of a species of Notidanus iu the Red 
Chalk of Speeton, when I visited that place in 1854. — Rev. T. G. Bonney, 
M.A., Westminster. 
REVIEW. 
Esquisse Geologique et FaUontologiqite des Couches Cretacres du Limhourg el pins 
spi'rhdenmit de la Craie Tiijfeau. By Jonkhk. J. T. B. van den Bink- 
HOKST. Parti. 8vo., pp. 268. FivePlates and a Geological Map. 1859. 
Maestricht. 
Limburg, a south-easterly province of the Netherlands, bounded by Prussia 
aud the jjrovinces of Liege and North and South Brabant, has been rendered 
accessible by the iron-roads of Prance and Germany to thousands of travellers 
aud tourists. Many of these, occupied their business or their pleasures, 
care but little perhaps for Limburg and its geological conditions : they might 
notice as they passed rapidly along that the country was for the most part 
level and sometimes marshy, and they might probably comment on its general 
productiveness or the luxuriance of its pasturage, but they might never care to 
inquire if it had any irou-miues or coal-mines, nor take the trouble to ask any 
questions about its stone-quarries. 
