LEPIDOPTEROUS FAUNA OF PORTLAND. 47 



100 yards of the mainland. There is not, therefore, any very great 

 barrier between Portland and the mainland. 



The localities on Portland may be roughly divided into the top 

 of the island, the undercliff, and the Chesil Beach. The top would 

 be, were it not for the quarries, very much like many of the downs 

 along the coast, and there are many pieces of undercliff here and 

 there between Sandsfoot and Purbeck not so extensive as that at 

 Portland, but of something the same character, with the exception 

 of the rocks and stones, and where one would expect to find the 

 same moths. 



The Chesil Beach between Portland Station and the Ferry Bridge 

 presents, perhaps, the greatest contrast to anything else in the 

 neighbourhood in its general characters, and it seems to me that it 

 is probably this strip of land which, to a great extent, at all events, 

 causes the peculiarities which exist in the Lepidopterous fauna of 

 Portland. 



It is most important to study all the fauna and flora of a portion 

 of land in order to get all the evidence we can on the subject of 

 its past history, but perhaps no part of the animal or vegetable 

 kingdom will give us so much trustworthy information as those 

 creatures which have very small means of locomotion. Amongst 

 these are the smaller moths, which are, as a rule, of very retiring 

 habits, and never go far from their food plants. They have a short 

 period of flight, perhaps an hour or less in the evening, and often 

 the same in the early morning ; during the rest of the night they 

 sit about on their food plants, or settle down in the herbage and 

 rubbish around them, and in the daytime many of them are scarcely to 

 be found at all, even when one searches most carefully and patiently 

 for them. Of course these remarks do not apply to all the small 

 moths, but only to the majority ; some are always ready to move on 

 the slightest provocation, and others are only rather sleepy during 

 the daytime and active at night. It must always, however, be 

 taken into consideration that most of these small moths are 

 entirely dependent for their existence on one, or, in some cases, two 

 or three plants, on which alone their larvae can feed, so that it is 



