182 ARTHROPODA 



the end of the telson. They form saccular diverticula be- 

 tween segments and in the telson. Where do they open into 

 the alimentary tract? 



5. Free the intestine, which is between the lobes of the 

 liver. The rectum is in the sixth abdominal segment. 



6. Pull back the anterior end of the stomach, identify the 

 circumesophageal connectives, in order not to destroy them, 

 and free the stomach by cutting the esophagus and intestine. 

 Examine the stomach under water. 



7. Trace the nerve chain. What ventral ganglia are 

 fused? The cerebral ganglia are most easily exposed by slic- 

 ing away, very superficially, the dorsal surface of the rostrum 

 and pressing the eye muscles apart. 



A drawing of the nervous system will be profitable. 



8. Trace the genital ducts to their external openings. 



MICHTHEIMYSIS (OR HETEROMYSIS) 



If living specimens are to be had, watch them swim, and 

 determine what parts are used in swimming. Does the ani- 

 mal swim in one direction or in both? 



1. Compare the body with that of a lobster. 



2. Are appendages present on each of the divisions of the 

 body? Compare them with the appendages of the lobster? 

 How do the thoracic appendages differ? 



3. Notice the statocysts in the tail fin. 



4. The living animal is transparent, and many internal 

 organs, such as heart, gills, and portions of the alimentary 

 canal, can be seen. 



// time permits, make a drawing. 



Bergh: Beitriige zur Embryologie der Crustacea. Zool. Jahrb. (Anat.), 

 6, 1893 



TALORCHESTIA (Beach-flea) 



These active little animals inhabit sand beaches, where 

 they burrow in the sand near high-water mark. Turn over 

 some of this sand and notice the activity of the animals that 

 are disturbed. (In the decaying vegetable matter which 



