PORIFERA. 169 



off the coast of Florida and its methods. The mode of 

 preparing sponges for the markets. 



2. What arguments can be advanced for thinking of 

 the sponges as colonial Protozoa? What is conclusive 

 for regarding them as really Metazoa? 



FIG. 45. Axinella polypoides, showing numerous oscula. After Schmidt. 



Questions on the Figure. What' are the principal external differ- 

 ences between Axinella and Leucandra (Fig. 44) ? How many in- 

 dividuals are represented here? What are your grounds for your 

 answer? Compare this with the skeleton of the sponge of commerce. 



3. The skeleton in sponges. Beside the differences in 

 material, in what different ways are these materials built 

 up in order to make a skeleton? 



4. What is the advantage in having the water pass in 



