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spaces. On the north, in Middlesex, we have Hyde Park, a good deal 
of still open land round Chiswick, and Osterley Park. In Surrey, 
Putney Heath, Wimbledon Common, Barnes Common, Richmond 
Park and Ivew Gardens are all legitimately included. 
In order to study the present Micro-lepidopterous Fauna of the 
London District it seems unnecessary to go back far into geological 
times, for I do not believe the strata lying below the present surface 
will be likely to yield us any knowledge bearing directly on the micro- 
lepidoptera which now inhabit the district. We have, then, only to 
deal with the actual soil which nourishes the vegetation on which these 
small insects almost entirely depend. 
The subsoil everywhere in the area is the Blue clay of the lower 
Eocene period. This is nearly always capped by sands or gravels, the 
oldest of which is the Bagshot sand, which occurs as an outlier in the 
south end of Richmond Park. 
The Plateau gravels, which were deposited at a very much later 
period, occur on the higher parts of the district in Richmond, Putney, 
and Wimbledon, while those known as the Low level gravels, a still 
later deposit, are found at Charing Cross, Hammersmith, Chiswick, 
Kew, and other parts. In some places, such as Fulham, Shepherd’s 
Bush, parts of Chiswick and Acton, and the south part of Kew Gardens, 
the gravel takes a more argillaceous character and forms a rich soil, 
known as brick earth, from the facility with which it can be burnt 
into builder’s bricks. Lastly, in stretches along some portions of 
the river side, there is a fine deposit known as alluvium. The 
bearing of these different formations on the micro-lepidoptera is of a 
secondary nature, apparently affecting them only so far as the different 
soils are more or less suitable to different plants. In the heavier clay 
lands we find rather wet meadows with oaks, elm, and wild roses in 
the hedges, while in the more sandy or gravelly districts we have heath 
lands with broom, gorge, and the finer-leaved grasses, the trees being 
birches and firs, with here and there, dwarf willows (Salix repens) in the 
damper spots. With regard to its physical features, the district may 
be looked on as a level valley, with the Thames flowing at the bottom 
and the land sloping more or less gradually upwards on each side. 
As the tides flow up from the sea, practically throughout the whole 
district, it must of necessity be fairly level in its lowest portion, and 
the flats along the river side do not rise above 13 feet above sea level 
in many places, and are frequently covered with water at the flood 
tides. The highest points in the district lie, I believe, under 200 feet. 
Hyde Park may be taken as lying between 50 and 100 feet, while 
Barnes Common ranges from 20 to 46 feet. In the mile of road 
between the river and Putney Heath there is a rise of 130 feet, and 
this rise is continued over Wimbledon Common nearly to 200 feet. 
Richmond Park rises to 165 feet near Richmond Hill Gate, but is 
mostly under 100 feet above sea level. The mean annual temperature 
is about 49°, and the rainfall about 25 inches per annum, but the 
average amount of sunshine is decidedly low, being little more than a 
quarter of what might be experienced. The climate may then be 
considered, compared with the rest of England, as rather warm, fairly 
dry but for the river mists, though deficient in sunshine. It will be 
seen then that the whole district lies at a very low level, that there is 
