Plate 30. 



Fig. 1. Obelia dichotoma. Magnified view of a part of the hydroid. 



Agassiz Laboratory, Newport, Rhode Island, June 28, 1895. 

 No. 2. Obelia dichotoma. Magnified view of one of the polypites of fig. I. 

 No. 3. Obelia dichotoma. Magnified view of one of the medusa; immediately 



after being set free from the hydroid represented in figure 1. 



The gonads are now adjacent to the manubrium. 

 Fig. 4. Obelia dichotoma. The medusa 3 days after being set free from the 



hydroid, showing how the gonads have migrated outward down 



the radial-canals. 

 Fig. 5. Medusa of Obelia sp. Showing the bell inverted. This" attitude is 



often assumed by the young medusa. Newport, Rhode Island. 

 Fig. 6. Medusa of Obelia sp. Oral view of mature medusa. Newport, 



Rhode Island. 

 Fig. 7. Stomotoca ptcrophylla, Nassau Harbor, Bahamas, April 20, 1907. 



Natural size. Normal aspect of the medusa. Compare with 



figure 3, plate 29. 



See page 113; volume 1, for description of figure 7. 

 Drawn from life, by the author. 



