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THE BRITISH WOODLICE.




This monograph first appeared in the "Essex Naturalist" (Volume XIV.,
1905-6) and has been republished by special arrangement with the
Council of the Essex Field Club.




THE BRITISH WOODLICE.

BEING

A MONOGRAPH OF THE TERRESTRIAL ISOPOD CRUSTACEA

OCCURRING IN THE BRITISH ISLANDS.

BY

WILFRED MARK WEBB, F.L.S.,

_Lecturer on Biology and Nature Study to the Surrey County Council,
Honorary Secretary of the Selborne Society, Sometime, Senior Assistant
Lecturer on Biology to the Essex County Council, and Editor of the
Journal of Malacology, Joint Author of_ "Eton Nature Study and
Observational Lessons."

AND

CHARLES SILLEM.

WITH TWENTY-FIVE PLATES AND FIFTY-NINE FIGURES IN THE TEXT.

  LONDON:
  DUCKWORTH & CO.,
  3, HENRIETTA STREET, COVENT GARDEN.
  1906.




PREFACE.


In Professor Sars' "Crustacea of Norway," quite a number of the British
species of woodlice are figured in detail and described in English, but
few copies of this fine work are to be met with in our country. The
Rev. Canon Norman has from time to time published notes on the British
species in "The Annals and Magazine of Natural History;" these are,
however, scattered, and contain but few figures, while other literature
that exists is out of date. Under these circumstances, we have thought
that the following account and figures of all the British species would
be useful to those anxious to work at the woodlice, and might also
encourage others to pay attention to the distribution and habits of the
interesting tribe to which they belong.

The writers would welcome any corrections or additions in view of a
second edition.

    W.M.W.
    C.S.

ODSTOCK, HANWELL, _December, 1905_.




CONTENTS.


                                                                 PAGE

  Introduction                                                     1
  Geological history                                               1
  External structure and appendages                                2
  Alimentary canal                                                 6
  Circulatory system                                               7
  Excretory system                                                 7
  Nervous system                                                   8
  Reproductive organs                                              8
  Development                                                      9
  Habits and Economic considerations                               12
  Local names                                                      15
  Methods of collections and preservation                          16
  Classification                                                   17
  Scheme of classification and synopsis of generic characters      18
  British Species                                                  19
  Section--Ligiae                                                   19
  Family--Ligiidae                                                  19
  Genus--Ligia Fabricius                                           19
  _Ligia oceanica_ Linze                                           19
  Genus--Ligidium Brandt                                           21
  _Ligidium hypnorum_ Cuvier                                       21
  Family--Trichoniscidae                                            22
  Genus--Trichoniscus Brandt                                       22
  _Trichoniscus pusillus_ Brandt                                   22
  _Trichoniscus vividus_ Koch                                      23
  _Trichoniscus roseus_ Koch                                       24
  Genus--Trichoniscoides, Sars                                     25
  _Trichoniscoides albidus_ Budde-Lund                             25
  Genus--Haplophthalmus Schobl                                     26
  _Haplophthalmus mengii_ Zaddach                                  26
  _Haplophthalmus danicus_ Budde-Lund                              27
  Family--Oniscidae                                                 27
  Genus--Oniscus Linne                                             27
  _Oniscus asellus_ Linne                                          27
  Genus--Philoscia Latreille                                       29
  _Philoscia muscorum_ Scopoli                                     29
  _Philoscia couchii_ Kinahan                                      30
  Genus--Platyarthrus Brandt                                       30
  _Platyarthrus hoffmannseggii_ Brandt                             30
  Genus--Porcellio Latreille                                       32
  _Porcellio scaber_ Latreille                                     32
  _Porcellio pictus_ Brandt and Ratzeburg                          33
  _Porcellio dilatatus_ Brandt                                     33
  _Porcellio rathkei_ Brandt                                       34
  _Porcellio laevis_ Latreille                                     35
  _Porcellio ratzeburgii_ Brandt                                   36
  Genus--Metoponorthus Budde-Lund                                  37
  _Metoponorthus pruinosus_ Brandt                                 37
  _Metoponorthus cingendus_ Kinahan                                38
  Genus--Cylisticus Schnitzler                                     38
  _Cylisticus convexus_ De Geer                                    39
  Family--Armadillidiidae                                           40
  Genus--Armadillidium Brandt                                      40
  _Armadillidium nasatum_ Budde-Lund                               40
  _Armadillidium vulgare_ Latreille                                41
  _Armadillidium pulchellum_ Zencker                               42
  _Armadillidium depressum_ Brandt                                 43
  Distribution of species                                          43
  Conclusion                                                       43
  Bibliography                                                     49




LIST OF FIGURES.


PLATES I.-XXV. with a List, will be found at the end of the Book.


FIGURE.                                                          PAGE.

  1. Parts of the body (_Oniscus asellus_)                         2
  2. The first antenna (_Oniscus asellus_)                         2
  3. The second antenna (_Oniscus asellus_)                        3
  4. The underside of the head (_Oniscus asellus_)                 3
  5. The mandibles (_Oniscus asellus_)                             4
  6. The first maxillae (_Oniscus asellus_)                        4
  7. The second maxillae (_Oniscus asellus_)                       4
  8. The fused maxillipeds (_Oniscus asellus_)                     4
  9. The "upper lip" (_Oniscus asellus_)                           5
  10. The "lower lip" (_Oniscus asellus_)                          5
  11. A typical thoracic segment (_Oniscus asellus_)               5
  12. The fifth thoracic segment of a female
        (_Oniscus asellus_)                                        5
  13. The underside of the abdomen of a female
        (_Oniscus asellus_)                                        6
  14. A typical abdominal appendage
        (_Oniscus asellus_)                                        6
  15. The first abdominal appendage of the male
        (_Oniscus asellus_)                                        6
  16. The second abdominal appendage of the male
        (_Oniscus asellus_)                                        6
  17. The alimentary canal (_Oniscus asellus_)                     7
  18. The circulatory system (_Oniscus asellus_)                   7
  19. The nervous system (_Oniscus asellus_)                       8
  20. Female reproductory organs (_Oniscus asellus_)               8
  21. The male reproductory organs (_Oniscus asellus_)             9
  22. The fertilized egg (_Porcellio sc