PLATE XXX. 



Clypei from the Infkrior Oolite. 



1 a. Clypeus Hugh. Agassiz, p. 375, upper surface, natural size. 

 h. Under surface of the same test, natural size. 



c. Lateral view of the same test, ditto. 



d. Posterior view of the same, showing the shortness of the anal valley, and the size of 



the vent, 



e. Ambulacra! area, zones, and inter-ambulacral plates, m,agnitied thrice. 



/. Apical disc, madreporiform body, and summits of the ambulacra, magnified. 



2 a. Clypeus Michelini, Wright, p. 369. Upper surface, natural size. 

 h. Under surface of another test, natural size. 



c. Lateral view of a, showing the obliquity of the posterior half of the dorsal surface. 



d. Ambulacral area, zones, and inter- am bulacral plates, magnified thrice. 



