Tlie King Crab. 1 1 5 



found. It extends from a point under the median eyes to 

 the posterior half of the abdomen. It has, extending ante- 

 riorly, a frontal artery which divides into a right and a left 

 anterior marginal artery} The marginal arteries bend out- 

 wardly, laterally, and posteriorly, following the curve of the 

 margin of the cephalothorax. The posterior marginal arte- 

 ries are the abdominal continuations of the anterior marginals. 

 Extending laterally from the heart are the lateral arteries. 



The "aortic arteries' 1 ' 1 take their origin from the anterior 

 end of the heart, and pass, one on either side of the cesopha- 

 gus, to the circum-oral reservoir t below mentioned. 



The first lateral arteries branch off from about the middle 

 of the cephalothorax ; the second and third lateral arteries, 

 from the posterior portion of the cephalothorax. From the 

 second, branches communicate with the marginal arteries 

 and with the hepatic arteries. The latter lie parallel to the 

 anterior marginal, and supply blood to the liver. 



The collateral arteries lie longitudinally, one on each side, 

 parallel to the heart. They connect the several lateral arteries. 



The heart is continued posteriorly by the superior abdomi- 

 nal artery. 



Branchial arteries pass from the abdominal collaterals to 

 the gills. 



The arteries of the ventral side cannot be now dissected. 

 They enclose the nervous system and consist of a circum- 

 oral reservoir, from which the crural arteries are given off 

 to the legs. Extending posteriorly from the reservoir is 

 the ventral artery, which gives rise to branchial and anal 

 branches. 



The blood is returned from the gills and all parts of the 



1 The frontal artery extends anteriorly to the margin of the cephalo- 

 thorax before dividing into the marginal arteries. 



