A HISTORY OF NORFOLK A slight preliminary sketch of its more important features may be useful. By great good fortune, records are preserved of some of the more interesting species in this county from a much earlier date than in most others. Thus with regard to that extraordinary species, Hypogymna dispar, of which the sexes are totally unlike each other ; which has so mysteriously disappeared altogether from this country, and yet by acci- dental introduction to the United States of America has so devastated vast tracts of woodlands that it has cost and is now costing the govern- ment of that country hundreds of thousands of dollars in the struggle for its extermination ; we are supplied with indubitable evidence of its former abundance with us. Mr. John Curtis writes thus {British Ento- mology, 1825—40) : ' It is not easy to conceive the delight I experienced when a boy on finding the locality for the "Gypsy moth." After a long walk I arrived at the extensive marshes of Horning in Norfolk, having no other guide to the spot than the Myrica gale, and on finding the beds of that shrub, which grows freely there, the gaily-coloured caterpillars first caught my sight. They were in every stage of growth, some being as thick as swan's quills. I also soon discovered the moths, which are so different in colour as to make a tyro doubt their being partners. The large loose cocoons were also very visible, and on a diligent search I found bundles of eggs covered with the fine down from the abdomen of the female. With eggs, caterpillars, chrysalides and moths I speedily re- turned, enjoying unmixed delight in my newly-gained acquisitions.' Now, although Myrica gale still flourishes in abundance at Horning there is no trace of the moth, and no evidence exists as to the date or means of its extinction. The Rev. T. H. Marsh however records its existence fur- ther west, at Cawston, not uncommonly, till 1861. Since that date it has apparently never been seen in Norfolk ; and except in most rare and casual instances, not within the British Isles. The fens of Norfolk extending for many miles along the banks of the Yare, the Bure, the Thurn and the Ant form still, with those of Cambridgeshire, the sole haunts in these islands of that handsome and striking butterfly the swallow-tail {Papilio machaon), a species which abroad is by no means confined to fens, but flies at large in most parts of Europe, even ranging over mountain districts, and in hotter regions, as in Asia, especially affecting such situations. Why it should with us so scrupulously attach itself to fens, hardly ever flying a mile away from them, is probably an insoluble mystery. Happily the fens themselves are so situated, and so extensive, that there is little risk of its extermination. This advantage it shares with species of similar proclivities, such as Spilosoma urtica, Arsilonche vemsa, Nonagria neurica, Meliana Jiammea, Hermima cribralis, Schoenobius mucronellus, S. gigantellus, Peronea shepherdana, P. lorquiniana, Phoxopteryx paludana, Ergatis subdecurtella, Xystophora palustrella, Laverna phragmitella, Cosmopteryx lienigiella and C. orichalcea, all of which are common to the Cambridgeshire fens as well as these. This protection is perhaps even more important in the cases of Lithosia muscerda, Calamia brevilinea, Chilo paludellus and Sericoris doubledayana, which seem 136
