22 FIRST LB880NS IN ZOOLO&T. 



Upon cutting a dry sponge in half there are to be seen large 

 canals which have large openings called oscula; these are 

 really openings for the exit of waste matters. Among these 

 large openings are multitudes of minute openings which 

 serve as mouths. These mouths lead by branching canals 



XTia. Vl.—Pheronema Annex, half natural size, with stellate and anchor -like 

 spicules, much enlarged. 



into little pockets or chambers which are lined with diges- 

 tive, ciliated cells; the sponge, then, has myriads of mouths 

 and stomachs (Fig. 18). 



Sponges develop, like all the higher animals, from true 

 eggs. The egg, after fertilization, begins to grow, and di* 



