— 31 — 



B. Sp., — blood Space. 



Hy. Nu., — hypodermic nuclei. -■--'TT 



B.c., — blood corpuscle. 

 Leu., — leucocytes. 

 Fig. 8. Section of the inner gill of Porcellio scaber. 

 Ch., — chitine. 



Hy., — hypoderm. V^ ■■^- 



P., — pillar. \^^. fk ■ 



B.c., — blood cavity. ''J^ . 



Plate II. 



Fig. 9. The ftrst right outer gill of Ligidium hypnorum, as viewed from the inner or dorsal side. 



In.ch., — incurrent Channel. 



Ex. eh., — excurrent Channel. 



Art., — articulation of the gill with the basal Joint. 

 Fig. 10. Cross-section of the gill of Ligidium hypnorum, taken in the dii'ection of the line ss', Fig. 9. 



Ch., — chitine. 



Hy., — hypoderm. 



W.b.c, — wall of blood cavity. 



Ex.ch., — excurrent Channel. 

 Fig. 11. The first right outer gill of Oniscus viurariiis, male, as viewed from the inner or dorsal surface. 



In.ch., — incurrent Channel. 



Ex.ch., — excurrent Channel. 



Ed.ch., — radiating Channels. 



Art. — articulation of gill with the basal Joint. 

 Fig. 12. Cross-section of the gill, taken in the direction of the line ss', Fig. 11. 



Gh., — chitine. 



Hy., — hypoderm. 



Hy.pl., — hypodermic pillar. 



v.b.c, — ventral blood Chamber. 



d.b.c, — dorsal blood Chamber. 



Pt., — double-walled partition between the dorsal and ventral blood Chambers. 



Fk., — forking of the partition. 



W.b.c, — walls of blood Chambers. 



In.ch. — incurrent Channel. 



Ex.ch., — excurrent Channel. 

 Fig. 13. Cross-section of the special part of the gill, taken in the direction of the line RR', Fig. 11. 



Gh., • — chitine. 



d.a.c, — dorsal air Chamber. 



v.a.c, — ventral air Chamber. 



d.b.c, — dorsal blood Chamber. 



v.b.c, — ventral blood Chamber. 



ra.b.c, — middle blood Chamber. 



Hy.pL, — hypodermic pillar. 



W.b.c, — walls of blood cavity. 

 Fig. 14. The course of the circulation of the blood in the gill of Oniscus murarius. The dotted arrows show 

 the direction taken by the particles of incurrent or venous blood ; the lined arrows that of the excur- 

 rent or arterial blood. 



