20 ANIMAL RESOUECES OP THE UNITED STATES 



60. ECHINODEEMATA— Continued. 



Injurious traits : 



Burrowers, (various echinoids.) 

 Destroyers of useful mollusks. 



61. CCELENTERATA. (Acalephs, polyps, &c.) 



Useful products: Coral, various species of polyps.) D. 17. 

 Injurious traits: Clog seines, weirs, and fishing-lines, (acalephs.) 



XV. PROTOZOANS. 



€2. BHIZOPODA. (Sponges and foraminifera.) 

 Useful products : 



Food, "mountain meal," (foraminifera.) D. 1 

 Infusorial earths, (foraminifera.) D. 18. 

 Sponges, used in arts and manufactures. D. 26. 



