CCELENTERATES, SPONGES, AND PROTOZOA 163 



SPONGES AND ANIMALCULES (PORIFERA AND PROTOZOA) 



Comparatively little is known about the feeding habits of the 

 animals belonging to the two lowest phyla of the animal king- 

 dom PORIFERA (Sponges) and PROTOZOA (Animalcules), and as, 

 apart from certain parasitic forms which will be dealt with else- 

 where, the food is for the most part of mixed character, we 

 may now proceed to consider a few types, from Mammalia down- 

 wards, in which there are interesting adaptations to a diet entirely 

 or mainly of vegetable nature. 



