The Worh of the Geological Survey. 161 
one of the earliest formed, and is still, perhaps, the most illustrative 
in the country. 
The fossils are arranged stratigraphically, and furnish the basis 
on which the Survey maps of the fossiliferous formations have been 
constructed. Every important subdivision of the Palaeozoic, Secondary, 
and Tertiary systems is represented by a full series of its character- 
istic fossils gathered from the various districts in the British Isles 
wherein it is developed. These are arranged and tableted in such a 
way as to be readily accessible to the public. Those who wish to 
follow out the palaeontological details of the Survey maps and 
memoirs, or to study general text-books of the science, have thus the 
fullest opportunities afforded to them. 
The palaeontologists, with their assistants, are continually engaged 
in arranging and re-tableting the collections to make room for fresh 
material received from the officers in the field, from donations, or 
from purchase. Catalogues of the fossils in several departments 
have been prepared and published. 
The Rock-collection has in recent years been greatly increased 
and entirely re-arranged so as to bring it abreast of modern petro- 
graphy. It includes a collection of rock -forming minerals in illustra- 
tion of the characters of the more important minerals that enter 
into the composition of rocks ; a series of typical rocks, named, 
classified, and so arranged close to the eye that the visitor may have 
no difficulty in observing their general external characters ; a section 
devoted to illustrations of various geological structures, such as 
cleavage, jointing, foliation, plication, the structures of igneous 
rocks, the effects of contact-metamorphism, the markings made by 
glacier ice, and the results of weathering in different rocks. But the 
chief part of the collection is a series of British rocks arranged in 
stratigraphical order from the oldest gneisses up to the most recent 
shell-sand. Not only are the sedimentary rocks represented in this 
series, but a large suite of igneous rocks is included, so that the 
student of volcanic history may see samples of the lavas and tufts 
which have been ejected at each of the periods of volcanic activity 
in the geological annals of Britain. Diagrams and maps are placed 
near the specimens to show the geology of the districts from which 
the latter were taken. Illustrations are likewise given of tire more 
important microscopic structures met with in rocks, and especially 
among those of Britain. A handbook is being prepared to this part 
of the Museum, which it is hoped may prove to be a useful aid to 
students of petrography. 
The Geological Survey collections in the museums in Edinburgh 
and Dublin are set out on similar lines. They have been arranged 
stratigraphically to elucidate the maps, sections, and memoirs, and 
furnish a tolerably full series of specimens in illustration of the 
geology of each kingdom. A handbook for the Edinburgh gallery is 
published, and one for that of Dublin is nearly ready. 
VOL. V. T. S. — 1 7 
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