246 ECHINODERMATA (tHE STARFISH) 



4. The Water Vascular or Am]:)ulacral System is the means of 

 locomotion. 



(1) The Ampullae. Along the floor of each ray of an in- 



jected specimen find numerous vesicles or sacs. 



(a) Shape? 



(b) Size? 



(c) Color? 



(d) Number of rows? Number in each row? 



(e) Total number for the ray? Estimated number for 

 the starfish? Use? 



(f) How are these ampullae connected with the tube feet? 



(g) How are they (the ampullae) connected with each 

 other? 



(2) Sketch plan of the ambulacral system. 



SYSTEMATIC STUDY FOR BRANCH ECHINODERMATA 



1. Plan of Structure. Look carefully at the sea-urchin and 

 sea-cucumber and others for the plan of five in the divisions or 

 organs of the body. 



2. Symmetry. Radial, or bilateral, or both? 



3. Water Vascular System. Present or absent? 



4. The (animals examined) have the following 



branch characteristics: (Student name them.) Hence they 

 belong to Branch Echinodermata. 



SYSTEMATIC STUDY FOR THE CLASSES OF ECHINODERMATA 



Use a starfish, a sea-urchin, a sea-cucumber, or good pictures 

 of the representatives of other classes. 



1. Is this animal fixed or free? 



2. Body with central disk and pentameral rays, globular with- 

 out rays, long and cylindric, or with an acorn-like top on a lonp; 

 flexible stalk? 



3. Arms or rays. 



(1) Number? 



(2) Are the cecal processes contained in the arms? 



4. Tentacles present or absent? 



5. This animal has the following characteristics : 



hence it belongs to Class 



Remark. — Consult descriptive zoologies for Classes of 

 Echinodermata. 



