20 ANIMAL RESOURCES OF THE UNITED STATES 
60. ECHIN ODERMATA—Continued. 
Injurious traits: 
Burrowers, (various echinoids.) 
Destroyers of useful mollusks. 
61, CQALENTERATA. (Acalephs, polyps, &c.) 
Useful products: Coral, various species of polyps.) D. 17. 
Injurious traits: Clog seines, weirs, and fishing-lines, (acalephs.) 
XV. PROTOZOANS. 
62. RHIZOPODA. (Sponges and foraminifera.) 
Useful products: 
Food, “mountain meal,” (foraminitera.) D.1 
Infusorial earths, (foraminifera.) D. 18. 
Sponges, used in arts and manufactures. D. 26. 
