A Bracliyuran Crustacean. 107 



Remove the second antenna. Do you find the elongated 

 filament that was specially developed in the lobster? Can 

 you find the openings of the green-glands ? 



Draw a second antenna. 



Carefully remove the first antenna. Find the position of 

 the auditory sac. Do you find the representatives of the 

 terminal filaments QfHomarus? Which filament is provided 

 with numerous sensory hairs? 



Draw. 



Do the compound eyes differ from the same of the lobster? 



Draw. 



Without injuring the gills, remove the right branchial 

 wall. Pleurobranchia will be found on the fifth and 

 sixth thoracic segment ; arthrobranchia, one on the sec- 

 ond, two on the third, and two on the fourth ; while 

 podobranchice are found only on the second and third 

 thoracic segments. 



Remove one of the gills, and see how its structure differs 

 from that of the gill of the lobster. 



Internal Anatomy. Carefully remove the dorsal por- 

 tion of the carapace. Cut away the underlying integument, 

 and expose the viscera. Cover the specimen with water, 

 and, without displacing or injuring the organs, note as fol- 

 lows : 



The heart and its two pairs of cardiac apertures or 

 valves; the pericardial sinus ; the openings into the sinus of 

 the branchio-cardiac canals; the ophthalmic artery; the 

 antennary artery; the hepatic artery; the superior abdom- 

 inal artery. 



Somewhat anterior to the heart lies the stomach. Com- 

 pare with Homarus. Note the arrangement of the dorsal 



