' A MANUAL OF ZOOLOGY ' 23 



lat is its relation to the mouth? Describe the oesopha- 

 s, leading from the mouth to the stomach. Note' the 

 diac and the pyloric regions of the stomach. With 

 ssors remove the wall "of the stomach and note the 

 •d portions or ossicles. Do they have any definite ar- 

 igement? How are they arranged? How m'any Of them 

 ! there? The gastric teeth will now be seen: a pto of 

 eral teeth, and a median tooth. Demonstrate the motion 

 these teeth. Is there any division between the two 

 ;ions of the stomach? Trace the intestine from the 

 mach to the anus. Note an enlargement near the 

 sterior end, the coecum. Look for folds on tlie inside 

 the intestine. At the sides of the stomach will be found 

 obulated mass, the digestive glands. Try to find the 

 3t leading to the stomach. 



The excretory system consists of the green glands or 

 Ineys In the lower side of the head. Trace the duct 

 m these glands to its opening at the base of the -antenna, 

 lat name will be given to this duct? 



THE REPRODUCTIVE SYSTEM— In the male the 

 ites will appear as tubular organs extending from the 

 eral angles of the stomach into the abdomen. In the 

 lyfish they differ in being bilobed anteriorly. If a live 

 scimen is at hand cut the testes and examine some 

 the fluid for sperm cells or spermatozoa. 



Trace the tube (vas deferens) of the testes to its 

 ternal opening. In the female the ovaries compare in 

 3ry respect with the testes of the male. Some may have 

 ?s~in them. Trace the oviduct to its external opening. 



THE NERVOUS SYSTEM— To study this it will be 

 cessary to remove the muscles and viscera. Begm 

 th the abdominal ganglia and carefully trace the chain 

 jhalad through the thoracic ganglia Jo th'e sub-oesopha- 

 i\ ganglion, thence by a pair of nerves around the 

 sophagus to the supra-oesophageal ganglion, or brain. 

 te the number of ganglia in each ca se and make drawing 

 show the nervous syste m. ^ living specimen should 

 w"Be" at hanSi IHace it in a jar of water. Note its 

 ivements. Does it swim? Tabulate the different move- 

 mts observed. Place some meat or bread in the jar of 

 ter some distance from the specimen and cause currents 



