REVIEW. 



417 



died ill coral-mud impregnated \nth silicic acid, would they have been pre- 

 served ? — Yours, A., Land's End. — ^Mineral-veins cannot, in the sense tlie 

 question is put by our correspondent, be said to be due to sedimentary deposits. 

 In some cases they present the appearance of stratification, as in those 

 instances of tilled-up cavernous hoUows noticed and described in the papers by 

 Dr. Watson, in vols. i. and ii. of this magazine. Air. Salmon's articles on ore- 

 veins, commenced in our last number, tvtLL also give our correspondents much 

 information on this topic. 



Certiiin bands of ironstone-nodules ai'C interstratified in the sedimentary beds 

 of the Inferior Oolite and of the Lias. The Lower Greensand of the Cretaceous 

 group, and the basement -bed" of the London Clay amongst the Tertiary rocks 

 offer instances of sedimentary strata being so highly impregnated wiih mineral 

 matter as to be sometimes equivalent in metallic riclmess to the miiieral-veins. 

 The ii-onstone-nodides and strata of the TTealds of Kent and Sussex were in 

 Roman and mediieval times largely worked as ores, but mineral-veins proper 

 cannot be regarded as contemporaneous formations with the strata in winch 

 they 0CCU1-. 



Ehrenberg is the great authority on Infusoria. A very nice condensed 

 account of this class was pubKshed some years since by Mr. Prit chard, the 

 optician and niicroscopist, and a new edition has been more lately produced. 

 Dr. ManteU has given an account of some British species in a very interesting 

 little volimie. The " Micrographical Dictionary" gives a vast amount of ui^ 

 formation about Infusoria ; and there is a goo^ article on the subject in the 

 " Cyclopedia of Anatomy and Physiology." 



It is not in every case, as rightly suggested, that organic objects ai-e pre- 

 served; the circumstances attendant on their fossdization must of coiu'se be 

 exceptional. 



EossiLS OF THE Eed Chalk. — I am able to add one species to the Terte- 

 brata in the list of fossds given by ^h. T\'iltshii-e in his mteresting paper on 

 the " Red Challv." I found a tooth of a species of Xotidanus in the Red 

 Chalk of Speeton, when I visited that place in IS5I:. — Rev. T. G. Bo>"^'ey, 

 M.A., "Westminster. 



EE VIEW. 



Esqidsse Gt'ologique et Paleontologiqite des Couches Cretactes du L'mlourg et plus 

 spkicdement de la Craie Tnffeau. By Joxkhe. J. T. B. van den Bink- 

 HORST. Parti. Svo., pp. 268. Eive Plates and a Geological Map. 1^59. 

 Maestricht. 



Limburg, a south-easterly province of the Xetherlands, bounded by Prussia 

 and the provinces of Liege and ^orth and South Brabant, has been rendered 

 accessible by the iron-roads of Prance and Germany to thousands of travellers 

 and toiuists. Many of these, occupied with 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 iron-mmes or coal-mines, nor take the trouble to ask any 

 questions about its stone-quarries. 



