106 ANNELIDA. 



(d) The connectives that join the supra-esophageal ganglia 

 to the first pair of the ventral chain, the infra-esophageal ganglia. 



(e) The nerves that run from the supra-esophageal ganglia 

 to the eyes. 



(/) There are three stomo-gastric ganglia, one on each side 

 of the muscular lobes of the buccal pouch and one on the median 

 line. These are joined to the supra-esophageal ganglia. 



Draw the nervous system. 



8. Open the buccal cavity by cutting along one side and 

 notice the three large buccal muscles, one dorsal and two 

 lateral. These bear many minute denticles that may be seen, 

 in the right position, with a compound microscope. It is by 

 means of these that the leech makes its wound. 



GEPHYREA. 



PHASCOLOSOMA. 



This form is commonly found buried in sand between tide- 

 marks. Specimens sometimes occur on the same flats with 

 Nereis, but they are generally more abundant where the mud is 

 of a slightly different, more sticky character. 



1. Handle a living specimen and see how turgid it is. If 

 you touch a specimen that has been allowed to expand in a dish 

 of sea-water you will find it is rather soft, but becomes turgid 

 immediately upon being touched. How is this accomplished? 



2. Examine a living animal in a dish of sea-water. The 

 anterior portion of the body, the introvert, is drawn in, but may 

 occasionally be extended, when it will be seen to bear at the 

 anterior extremity a crescentric crown of tentades, which partly 

 surrounds the mouth. 



3. Compare with a preserved specimen which has been killed 

 with the introvert extended. 



Make drawings showing the animal with the introvert pro- 

 truded and with the introvert concealed. 



4. The anus is located on a dorsal papilla, anterior to the 

 middle of the body. Near the anus a pair of lateral papillae 

 mark the position of the nephridiopores. The coiled intestine 



