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120 of each stratum. The collection is, as our readers well know, arranged on a stratigraphical plan; and by the use of coloured tablets, in walking past cases we see at a glance the fossils we ought to find in any ordinary locality of every geological formation. To the student this is a facility of the highest value, and enables him, whether studying for a class or preparing for a full excursion, to learn with certainty and ease the essentially typical fossils of every stratigraphical group or of the district he is visiting.

Not a less happy idea was it to illustrate or rather to explain the map-sheets of the Survey, by short memoirs of the geology of the districts they represent. Thus, the fluvio-marine beds of the Isle of Wight have been described by Edward Forbes; the country round Cheltenham, by Mr. Hull; parts of Wiltshire and Gloucestershire, by Professor Ramsay; the South Staffordshire Coal-field, by Mr. Jukes; the Warwickshire Coal-field, by Mr. Howell; the country round Woodstock, the country round Prescot, in Lancashire, parts of Oxfordshire and Berkshire, and the Wigan Coal-field, by Mr. Hull; part of Leicestershire, and parts of Northamptonshire and Warwickshire, by Mr. Aveline. The West Indian surveyors have followed this excellent example, and we have had a memoir on the geology of Trinidad, by Messrs. Wall and Sawkins.

Two others just issued are before us, 'The Geology of Parts of Oxfordshire and Berkshire (Sheet 13),' by Messrs. Hull and Whitaker; and 'The Geology of Parts of Berkshire and Hampshire (Sheet 12),' by Messrs. Bristow and Whitaker.

The Geologists' Association are about to take again their summer excursions: how admirably instructive it would be to take one of those geological spots in Berkshire or Hampshire, which Mr. Bristow so faithfully and accurately describes in this little eightpenny Memoir; and with the geological map of the district, Mr. Bristow's descriptions of the sections and other exposures of the strata, of their order, sequence, and mineral characters, and Mr. Etheredge's lists of fossils, how much more instruction would be got out of some of those pleasant holidays than can ever be attainable under the best desultory leadership!

In Mr. Hull's 'Oxfordshire' a small coloured geological map is inserted, reduced by photography from the larger Ordnance sheet, so that we have in it map and text for a week's good geological labour. In Mr. Bristow's Memoir, the cretaceous rocks and tertiaries from the Eocene of Woolwich and Reading to the alluvium of the Kennet, is treated in a masterly manner, and illustrated by well selected woodcuts. The cretaceous deposits and tertiaries, as also the oolitic series, form the topics of Mr. Hull's 'Memoir on Oxfordshire and Berkshire,' and, we need scarcely say, are treated in an equally able manner.