6o 



COELENTERATA 



and endoderm. The endoderm contains large feeding cells with 

 pseudopodia and flagella, digestive cells (gland cells), and muscle 

 fibers. (Figure 23.) 



Fig. 24. Portuguese man-of-war, Physalia, sheltering several shepherd fish, Nomeus, 

 amid its tentacles. (Courtesy of American Museum of Natural History.) 



Alternation of Generations {Metagenesis) in the Hydrozoa. — 



In Obelia, there are two types of zooid. The reproductive one, called 

 the gonangium^ produces ectodermal medusa-buds along the blasto- 



