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��gatliorcci ill the siiine middle cretaccoua strata of ' wcBtcrn Kansa8 ' referred to a momeDt ago- Prized moi-e highly than even these, how- ever, are the hundreds of skeletons, or parts of skeletons, of gigaotlc walking aud swimming reptiles, herbivorous and carnivorous, which inhabited the cretaceous ocean, and basked upon the shores of the islands of that age, now forming the heights of the Itockies.

Among the earliest were disclosed wonder- fully preserved bones of the class of mosasau- roid reptiles. — a gronp, which, though rare in Ruroi^G, here attained an enormous develop- inent, both in numbers and in variety of forms. Nearly seventeen hundred individuals, of this kind of giant-reptile alone, stand on the mu- seum's catalogue.

The land-forms were even more terrible to the imagination, though their food was vege- table, and their disposition probably peaccM. One such sauropodan dinosaur shown to the public was sixty feet in length, and in general form came nearer to a crocodile than any thing else. A thigh-bone, lying in au exhibition case, measures sis feet in length and is solid ; BO that it was well able to support the weight of the monster as it rose, kangaroo- fash ion, on its hind-legs, to browse its food or to look about it.

In another colossal reptile (Apatosaurus) of nearly equal proportions, cue of the neck- vertebrae is shown which is three and a half feet in diameter : while the ponderous bones of Brontosanrus prove, that, when living, the ani- mal must have weighed twenty tons or more. The smallest part of it is the head ; the skull and brain beiug more diminutive, in proportion, tliau in the case of any other animal now known. It had no weapons of offence or de- fence, nor even any armor : but in another genus (Stegosaurus) approaching it in bulk, though of more compact form, the body was protected by massive plates, and armed with long spines. This exaggeration of a cross between a snapping- turtle and a hedge-h(^ possessed a singularity in struclure, sitiee in one of the vertebrae of the haunch is a large neiTC- cavity, which contained a second or posterior brain, supplementing the extraor- dinarily small nerve-centre in the skull. This feature has no parallel in tlic animal kingdom. To Professor Marsh's personal collection somewhat has been added at the museum by the U.S. geological sur\ey, which will become the publisher of the outcome of hia studies now in progress. A score or so of assistants are conslantly onduty, cither in study, or in lUc

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mechanical work of skilfully extracting fossils iVom the rocky matrix ; in matching and mount- ing by the aid of wire, clay, and piaster, for permanent presenation, the often badly broken bones of some antique brute whose extinction most of the world can accept with resignation ; or in making casta, models, and drawings of fossils, original and ' restored.'

Several quarto volumes are .-ilready under way ; and scarcely an issue of the American journal of science appears, withont an advance note of some special discovery in vertebrate paleontology, anticipating the completer de- scriptions to be made from this museum's ricli materials. F.bnf-st iNr.KitsoLi,.

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��RIVER-POLLUTION IN ENGLAND.

After a delay which is much Xo be rcgi'stted, the Englitil] government has printed the reports left by Dr. Angus Smith on the working of the Alkali-works regulation act and the Rivets-poll ution prevention act. As we mentioned at the time of Dr. Smith's death, he attached great imponance to bia examination of polluted waters. Great improvements have been effacted in lessening the injurious vapors from cbami- cal works. The new works registered are engaged chiefly in the manufMture of sulpbate of ammonia and chemical manure. The smaller gas-worka have found that tbey can more profitably manufacture and sell sulphate of animonla than. send Iheir gas-liqnor to a distance. The direction* in which improvements have latterly been most marked have been in the treatment of aulphurelted hydrogen evolved in the manufacture of sulplialenf ammonia, and in the wash- ing of the gawB evolved In the treatmentof coproHtea and oiher malcrlala at the chemical works. In the former case, oxide-of-iron purifiers have been erected as the best means of preventing the CKape of sul- phuretted hydrogen; and in some works this gaa ia now completely burned, instead of bping allowed to escape uubumt, up the chimney, as formerly. At others, Claua's method of burning so as to form sul- phur, which is collected, and not sulphurous acid, has been adopted. Dr. Smith maintains, that, what- ever process be used, the limit of sulphurous acid allowed to escape should not exceed tive-tenths of a grain per cubiu foot, including the acidity of the coal- smoke Itself, which latter varies from a quarter to half a grain. The escapes from sulphuric-acid works have been considerably redaced, in consequence of the Introduction of regular testing by manufacturers; and condensers to absorb the nitrous fumes have been put up in a number of nitric-acid works.

Dr. Smith's new method of tesUng with sugar the amount of organic activity amongst the microbes (at least, of a certain class) which exist in waters wu mentioned nearly a year ago in the technical journals. He found that in nearly all natural waters sugar fer- ments, and hydrogen gas is then idven oH. So faraa

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