﻿Supplement. 

 PLATE XLII. 



1 a. Cidaris Fowleri, Wright, p. 32. Test, with spines attached, of the natural size. 



b. Inter-ambulacral plate, zones, and ambulacral area, mngnified. 



c. Primary tubercle, magnified. 



d. One of the jaws, magnified. 



e. One of the primary spines, magnified twice. 



/. One of the secondary spines, magnified three times. 



2 a. Hyboclypus agariciformis, Forbes. Upper surface, natural size, showing the 



apical disc in situ. 



b. Under surface of the same, natural size. 



3. The apical disc of the same urchin, magnified twice. 



