56 



THE BRITISH WOODLICE. 



SCHEME OF CLASSIFICATION AND SYNOPSIS 

 OF GENERIC CHARACTERS. 



Order— ISOPODA. 

 Tribe— ONIStTOIDA. 



Section /.— LIGIiE. 



The Two Divisions of the Tail Appendages alike in Shape. 

 (A.) — Flagellum with 10 or more joints; tail appendages 

 wholly visible ; head without lateral lobes 



(i.) — Abdomen broad ; body large ; habitat 



the sea -shore - 



( 2 — Abdomen narrow ; habitat wet moss - 



(B.) — Flagellum with less than 10 joints ; head with 



small lateral lobes, tail appendages partly covered 



(3.) — Abdomen narrow ; eyes compound ; 



flagellum usually with .nore than 3 



joints .... 



(^.) — Abdomen narrow ; eyes simple or want- 

 ing ; flagellum with 4 joints - 

 (5.) — Abdomen broad (comparatively) ; eyes 

 simple ; back with longitudinal ; 

 ridges ; flagellum with 3 joints 



Section //.— ONISCI. 

 The Outer Divisions of the Tail Appendages Bvoadev than the Inner. 

 (A.) — Tail appendages projecting when the animal- is 

 walking ------ 



(a.) — Unable to roll up into a complete ball. 



(6.) — Flagellum with 3 joints ; abdomen 



broad ; head, with lateral lobes 



(7.)— Flagellum with 3 joints; abdomen 



narrow ; head without lateral lobes - 



(8.) — Flagellum with 1 joint ; eyes wanting ; 



abdomen broad ; habitat, ant's nests 



(9.) — Flagellum with 2 joints ; abdomen 



broad ; frontal lobe projecting 



(10.)— Flagellum with 2 joints; abdomen 



narrow .... 



(b.)— Able to roll up into a complete ball. 



(11.)— Flagellum with 2 joints ; antennae 



folded together over the thorax when 



the animal is rolled up into a ball 



(B.^ — Tail appendages not projecting when the animal 



walking ..... 



(12.) — Flagellum with 2 joints ; antennae 

 hidden or carried at the sides of the 

 head when the animal is rolled up 

 into a ball - Arwadillidium. 



- LlGIIDAK. 



Ligia. 

 Li g id him. 



Trichoniscid^. 



Trichoniscus. 



Trichoniscoides. 



Haploph thalm us . 



Oniscid^e. 



Oniscus. 



Philoscia. 



Platvarthrus. 



Poi-cellio. 



Metoponorthus. 



Cvlisticus. 



Akmadii.lidiid^. 



[To be continued.] 



