Transcriber's Note:

The twenty-five engraved illustrations of adult woodlice shown in Plates I to XXV at the end of the book have been prepared with thumbnails which preserve the same scale as the original book. Clicking on one of these thumbnail images, or on most other figures in the text, will display a larger image to the same scale.

Obvious typographical errors have been corrected. Inconsistent accents, punctuation, and hyphenation are as in the original text.

The "æ" ligature is used interchangeably with "ae" throughout.

Some taxonomic names may have changed since 1906.

For a complete list of corrections, please see the [end of this document].

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of Natural History;" these are, however, scattered, and contain but few figures, while other literature that exists is out of date.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—Ligiæ[19]
Family—Ligiidæ[19]
Genus—Ligia Fabricius[19]
Ligia oceanica Linzé[19]
Genus—Ligidium Brandt[21]
Ligidium hypnorum Cuvier[21]
Family—Trichoniscidæ[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—Oniscidæ[27]
Genus—Oniscus Linné[27]
Oniscus asellus Linné[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—Armadillidiidæ[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[45]

[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 scaber) after Roule10
[23.]The fertilized egg seen in section (Porcellio scaber) after Roule10
[24 to 31.]The development of a woodlouse (Porcellio scaber) after Roule10
[32.]Embryo of the woodlouse showing the three divisions of the intestine separately developed (Porcellio scaber) after Roule11
[33.]Embryo of the woodlouse showing traces of the segments (Porcellio scaber) after Roule11
[34.]An embryo woodlouse ready to be hatched (Porcellio scaber) after Roule11
[35.]Flagellum and last peduncular joint of the antenna of Ligia oceanica12
[36.]Flagellum and last peduncular joint of the antenna of Ligidium hypnorum13
[37.]Flagellum and last peduncular joint of the antenna of Trichoniscus pusillus23
[38.]Flagellum and last peduncular joint of the antenna of Trichoniscus vividus24
[39.]Flagellum and last peduncular joint of the antenna of Trichoniscus roseus24

[40.]Flagellum and last peduncular joint of the antenna of Trischoniscoides albidus25
[41.]Flagellum and last peduncular joint of the antenna of Haplophthalmus mengii26
[42.]Flagellum and last peduncular joint of the antenna of Haplophthalmus danicus27
[43.]Flagellum and last peduncular joint of the antenna of Oniscus asellus28
[44.]Flagellum and last peduncular joint of the antenna of Philoscia muscorum29
[45.]Flagellum and last peduncular joint of the antenna of Philoscia couchii30
[46.]Flagellum and last peduncular joint of the antenna of Platyarthrus hoffmannseggii31
[47.]Flagellum and last peduncular joint of the antenna of Porcellio scaber32
[48.]Flagellum and last peduncular joint of the antenna of Porcellio pictus33
[49.]Flagellum and last peduncular joint of the antenna of Porcellio dilatatus34
[50.]Flagellum and last peduncular joint of the antenna of Porcellio rathkei35
[51.]Flagellum and last peduncular joint of the antenna of Porcellio laevis35
[52.]Flagellum and last peduncular joint of the antenna of Porcellio ratzeburgii36
[53.]Flagellum and last peduncular joint of the antenna of Metoponorthus pruinosus37
[54.]Flagellum and last peduncular joint of the antenna of Metoponorthus cingendus38
[55.]Flagellum and last peduncular joint of the antenna of Cylisticus convexus39
[56.]Flagellum and last peduncular joint of the antenna of Armadillidium nasatum40
[57.]Flagellum and last peduncular joint of the antenna of Armadillidium vulgare41
[58.]Flagellum and last peduncular joint of the antenna of Armadillidium pulchellum42
[59.]Flagellum and last peduncular joint of the antenna of Armadillidium depressum43