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. 



