PLATE XXXIII. 



Clypeus MiiLLERi, Wnglit. 



From the Great Oolite. 



1. Clypeus Mulleri, Wrigld, p. 371. Upper surface of a large specimen lying on a 

 slab of forest marble, natural size. From Mr. Frederick Bravender's 

 Collection. 



2 a. Upper surface of a medium sized specimen from the Great Oolite, natural size. 

 h. Under surface of the same test, showing the central mouth-opening, natural size. 



c. Lateral view of the same test, showing the shelving character of the posterior half of 

 the upper surface. 



3 a. Common variety of the species, having the apical disc very ex-central posteriorly, 



natural size. 

 b. Under surface of the same test, showing the mouth-opening and peristome, ditto. 



4. Apical disc, showing the two pairs of large, triangular genital plates, the small 



oculars, the large madreporiform body, and single imperforate genital 

 plate, magnified about four times. 



5. Ambulacral area, poriferous zones, and inter-ambulacral plates, magnified four times. 



6. Portion of a poriferous zone, showing the inner round holes, the external slit-like 



apertures, and the tubercles on the septa, highly magnified. 



