THE BRITISH WOODLICE, 



43- 



from moist air, while the outer division (or exopodite) acts as a 

 protecting cover (fig. 14). In Povcelii", air-tubes (tracheae) may 



? ABDOMINAL 



APPENDAGES 



Bewzng 



» Telsori 



FIG. 13. — THE UNDERS 



JZxopodcte 



be present (see below). 



In the male the first 

 two pairs of abdominal 

 appendages are specially 

 modified, the inner divi- 

 sions (endopodites) being 

 long and pointed (figs. 15 

 and 16). The last pair, 

 or tail appendages, in the 

 male are often consider- 

 ably larger than in the 

 structures is sometimes of 



(EridopoaMe) 



IDE OF THE ABDOMEN OF A 



female. (Oniscus asellus.) 



female, and the form of these 

 value in classification. 



Alimentary canal. — The 

 main portion of the alimentary 

 system is, practically speaking, 

 a straight tube (fig. 17). Its 

 first part (not shown in the 

 figure) is a narrow gullet, which 

 after passing through the nerve 

 collar dilates to form a sort of 

 stomach. Into this the secretion 

 of four digestive glands is poured by two ducts. These glands 

 have a somewhat striking appearance, being yellow tubes spirally 



. — A TYPICAL ABDOMINAL 

 APPENDAGE- 



(Oniscus asellus.) 



Exo- 

 -podiit, 



Endopodiie 



FIG. 15. — THE FIRST ABDOMINAL 

 APPENDAGE OK THE MALE. 



(Oniscus asellus.) 



Erufopodife 



FIG. l6.— THE SECOND ABDOMINAL 

 APPENDAGE OF THE MALE 



(Oniscus asullus.) 



coiled, and they end blindly. From the stomach the intestine 

 runs to the hinder end of the body and passes under the heart. 



