710 THE AMERICAN NATURALIST. (VOL XXXII. 
mentary deposits, from the most recent on the east coast to the 
most ancient on the west, and includes numerous small sections 
of the strata observed and recorded by various geologists in 
different parts of England. There is also a series of small 
maps, colored to show the exposed area of each geologic 
formation, and placed next to the case containing the speci- 
mens illustrating that formation. The most important of the 
nine “type” collections are those bearing the names of 
Sowerby, Gilbertson, S. V. Wood, F. E. Edwards, and Thomas 
Davidson. The last three alone would be enough to establish 
the preéminence of the museum in invertebrate paleontology. 
Mineralogy.—The collection of minerals is probably the finest 
and most complete in the world. The aim of the trustees is 
to show all the definite mineral species that are known, in all 
their varieties of crystalline form, modes of occurrence, and 
associations with one another. They also aim to have speci- 
mens from all noteworthy localities, and itis a “special object 
that examples of each mineral species show its most complete 
development, whether in magnitude or perfection of crystals, 
in the color and limpid purity, or in any other important quality 
which may belong to it in its more exceptional occurrence.” 
In a wall case just outside the entrance to the main mineral 
gallery there is a very attractive display of polished samples 
of some of the rocks and minerals which are used for orna- 
mental purposes. The main hall or gallery is cased entirely 
with mahogany desk cases, except for four mahogany wall 
cases, two at each end of the room. The mineral collections 
include a series introductory to the study of minerals, embrac- 
ing a set of specimens illustrating the growth of some of the 
ideas now considered fundamental in the science, and other sets 
of fine specimens showing the characters of minerals (their 
crystalline: form, color, lustre, degree of transparency, streak, 
cleavage, etc.), and illustrating the terms used in their descrip- 
tion ; the systematic collection of species and varieties ; enclos 
sures in minerals; a series of crystals, natural and artificial ; 
and a large number of pseudomorphs. The mineral speci- 
mens which are too large for exhibition in the desk cases are 
installed in wall cases in a room called the “ pavilion,” beyond 
