PLANT-EATING CRUSTACEA 223 



the wheat-ears and attack the young grains, which become little 

 brown galls, known to farmers as " ear cockles ", " peppercorns ", 

 or " purples ". Other injurious species will be mentioned in the 

 section on economic zoology. 



LOWER INVERTEBRATES 



The phylum of Hedgehog-skinned animals (ECHINODERMATA) 

 includes voracious creatures like Star- Fish, which feed on animal 

 prey, Sea- Urchins which do this to a considerable extent but at 

 the same time do not despise vegetable food, and forms like 

 Sea -Cucumbers, Sea- Lilies, and Feather -Stars, which are non- 

 predaceous but live on food of both kinds. 



The three lowest phyla of the animal kingdom, i.e. Sponges 

 (PORIFERA), Zoophytes (CCELENTERATA), and Animalcules (PRO- 

 TOZOA) are in the main either carnivorous or else their food is 

 of mixed character. 



