39 
nowhere any chalk or limestone exposed on its surface, and that there 
are no forests, but only the remnants of them, now left. 
There can, of course, be no doubt whatever that the lepidoptera 
followed in the wake of vegetation as it spread from various sources 
over the London District. Therefore a study of the Flora of the 
district will be almost sure to throw some light on the immigration 
and progress of the lepidoptera, which at the present time constitute 
that part of the Fauna. 
The earliest accounts of this district go to show that the river 
wound its way among the marshes, swamps, and ponds, which 
extended on each side from somewhere about the spot we now call 
Blackwall to the place we now know as Mortlake. A good deal of 
heathland lay between the present sites of Westminster and Fulham, 
while beyond the fens to the north stood the great forest of Middlesex, 
with outlying portions spreading down to the river. The higher, less 
swampy, parts of the district which were not forest, being perhaps 
more sandy and poorer soil, were probably covered with heath and 
scrub. Such was the general idea of the landscape, as far as we can 
gather, when in the 4th century the Romans built Augusta on the 
hanks of the Thames, somewhere on the site of the present Walbrook. 
Long after this town had decayed, and the germ of the city of 
London had come into existence, we get another glimpse of the district, 
and find that much alteration has taken place. A good deal of the 
forest land, which appears to have existed till the end of the 12th 
century, has been cleared and converted into meadows and pasture 
land. Hence arose the pastures and farm lands which used to be one 
of the great features of Middlesex. As London greAV, and required 
more vegetables, the farm land was gradually turned into market 
garden grounds, and as London and its suburbs spread wider, many of 
the market gardens were covered with houses, and those lepidoptera 
which were not exterminated during the building operations had to 
continue their existence in the few square yards devoted to the private 
gardens or public parks and recreation grounds. 
Besides the forest, and occupying probably a larger total area, were 
the more sandy grounds covered Avith heath, gorse and broom, Avith 
brambles, blackthorn, and other Ioav bushes. These Avere also gradually 
enclosed, especially at the end of the 18 th century, and have now 
mostly shared the same fate as the forests. 
A once famous locality,Avhich Avasin this district, must be mentioned. 
It was known as Hammersmith marshes, and AA T as one of the special 
hunting grounds of the late Mr. Samuel Stevens. Here Lacema 
phrac/mitella was taken, as Avell as Leucania obsoleta, L. straminea, and 
Senta maritima. (See President’s Address, 1906.) 
The present micro-lepidopterous fauna of this district is probably 
only the remnant of a much more extensi\ T e one. Though we appear 
to have feAV actual records of the smaller species, yet, judging from the 
old records of the macrodepidoptera, I think Ave may fairly argue that 
the Tineina were also more numerous, both in species and individuals, 
in days gone by. Many species must haA r e become extinct in the 
district, and though doubtless a few have immigrated, their numbers 
have probably not counter-balanced the loss sustained through the 
species that haA r e died out. 
The number of species mentioned in this paper is less than one- 
