I. GEOLOGY. 827 



PLATE III. 



Figs. 1, 4, 5, 6, 7. Structures seen in a thin section of spherulitic obsi- 

 dian from the lava stream of Rocche Rosse, in the Isle of Lipari. 

 8. Portion of one of the spherulitic bands in the above rock, x 22. 

 12. Magnetite crystals partially converted into peroxide of iron, occur- 

 ring in a crystal of leucite from Vesuvius, x 760. 

 2, 3, 9, 10, 11, 13, 14. Structures seen in a crystal of leucite, from 

 Vesuvius. 



PLATE IV. 



Perlite, from Buschbad, near Meissen, showing the spheroidal structures 

 lying between divisional straight lines F. F. F. F. 



3253. Map showing the work of the Geological Survey of 



Scotland, on the scale of one inch to the statute mile. All the 

 published sheets of the map are given here, and a few of which the 

 survey is completed, but which are not yet engraved, are inserted 

 in MS. At the foot of the map an example of .the horizontal 

 sections is given which are run across the country on the scale of 

 six inches to the statute mile. 



Geological Survey of Scotland, Prof. Geikie, F.R.S., Edin- 

 burgh,, Director. 



3254. Geological Map of the Ayrshire coal-field and adjoining 

 districts, on the scale of six inches to the statute mile. This map 

 has been selected as an illustration of the detailed work of the 

 Geological Survey of Scotland. The whole county is surveyed on 

 this scale, though only the mineral districts are published on these 

 maps, the general map of the country (see No. 3253) being on the 

 scale of one inch to a mile. At the foot of the map a MS. sheet is 

 inserted to show the stages of progress in the field work of the 

 survey. Two specimens are likewise given of the detailed vertical 

 sections, on the scale of forty feet to the inch, which are published 

 in illustration of the coalfields. 



" Geological Survey of Scotland, Prof. Geikie, F.R.S., Edin- 

 burgh, Director. 



3254a. Geological Map of England and Wales, by the 



late Sir Roderick I. Murchison, Bart., K.C.B., &c. Fifth edition, 

 with all the railways. Scale, 28 miles to an inch ; size, 14 inches 

 by 18. Edward Stanford. 



3254b. Geological Map of Ireland, by the late Joseph 

 Beete Jukes, M.A., F.K.S., Director of H.M. Geological Survey of 

 Ireland. This map is constructed on the basis of the Ordnance 

 Survey, and coloured geologically. It also shows the railways, 

 stations, roads, canals, antiquities, &c., and when mounted in case 

 forms a good and convenient travelling map. Scale, 8 miles to 

 1 inch ; size, 31 inches by 38. Edward Stanford. 



