The Lobster. 89 



angle of the heart. Each, in its course to the region of the 

 antenna, gives off, besides others, a branch to the lateral 

 walls of the stomach. Do you find the renal branch, dis- 

 tributed to the green-glands? 



Draw in the circulatory system on the dorsal view of the 

 animal already made, using a brush with light carmine paint. 



Press to one side the viscera, which hide the duct of the 

 mesenteric gland. A large artery, the hepatic, will be seen. 

 From what part of the heart does it take its origin ? .Does 

 it give off branches to other organs ? 



By the use of dots, rather than lines, designate its position 

 on the drawing. 



Turn the animal on its back, and through the transparent 

 wall of the abdomen note the inferior abdominal artery. 

 With a strong knife or with scissors, cut away the abdominal 

 sterna, and see if the artery sends out metameric branches. 

 Follow the artery anteriorly. It will be found to receive its 

 blood from the sternal artery, which also gives rise to an 

 anterior branch. 



The antero-ventral artery passes along the mid-ventral 

 line of the thorax. Name in order the branches that it 

 gives off to the thoracic appendages. \Yhat is its anterior 

 termination ? 



From the ultimate subdivisions of the main arteries, above 

 noted, the blood passes into certain sinuses, and from these 

 is sent to the subdivisions of the gills, through the afferent 

 branchial vessels, and there purified. Does your specimen 

 show the afferent vessels? After being purified, the 

 blood from the minute gill-filaments empties into the 

 efferent branchial vessels which unite to form the branchio- 

 cardiac canals. The latter lead from the region of the 

 thoracic epimera to the pericardium, where they empty 



