396 



CRUSTACEA. 



Fig. 201. 



A side view of the arterial 

 system in the Lobster. Nearly 

 one half of the body is re- 

 moved to show the deeper- 

 seated vessels : a, the stomach, 

 which has one half removed, 

 so as to show the cavity of that 

 viscus ; 6 b b, the intestine, 

 which is one straight tube; 

 ecc, the lobes of the liver of 

 the left side, the right being 

 removed ; d, hepatic duct, en- 

 tering the intestine ; e, the 

 heart ; fff, three orifices, 

 guarded by valves, whereby 

 the venous system communi- 

 cates with the heart ; g, the 

 anterior or antenna! arteries ; 

 A, the posterior or superior 

 caudal artery; t, the hepatic 

 artery ; k, a large artery going 

 down from the posterior end 

 of the heart, principally sup- 

 plying the feet and gills (ster- 

 nal artery) ; I is a small ar- 

 tery passing back along the 

 under surface of the tail, and 

 lost in the muscles of that part 

 (inferior caudal artery) ; m, 

 the trunk of the artery k bent 

 forwards along the fore part of 

 the thorax, giving off" branches 

 on each side to the feet and 

 gills ; n n n, the branches going 

 to the feet ; o o o, the branchial 

 arteries. 



