24 STUDIES OF ANIMAL LIFE. 



Can you see any reason for this animal's scientific 

 name, Gonio-nemus = bent-thread ? ^ 

 b. Bunches of nettle cells on these tentacles. 



2. Balancing Organs. 



The balancing organs are tiny sensory structures ar- 

 ranged around the edge of the " umbrella " like a 

 string of beads. 



a. Compare the number of these organs with that 

 of the tentacles. 



b. What is their arrangement with reference to the 

 tentacles. 



3. Prominent convoluted structures. (These contain 



either egg- or sperm-cells.) 

 a. How many of these structures are there ? 



4. The Velum. 



The velum is a delicate membrane extending inward 

 from the margin. 



5. The Manubrium. 



The manubrium corresponds in position to the handle 

 of an umbrella and contains a part of the diges- 

 tive cavity. 



6. The Mouth. 



The opening into the digestive cavity at the end of 

 the manubrium. 



C. Drawing's. 



1. Sub-umbrella view (4 cm.). 



2. Side view. (Make it diagrammatic.) 



D. Application of Coelenterate Studies. 



1. Show by a series of diagrams how the hydro-medusa 

 resembles in its plan of structure the Hydra and 

 also the hydranth of a hydroid. 

 1 This question applies only to Gonionemus vertens. 



