PLATE XXXVIII. 



Pygurus Blumenbachii, Koch and Bunker. 

 From the Coralline Oolite. 



1 a. Pygurus Blumenbachii, Koch and Bunker, p. 400. Upper surface, natural 



size. 



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



c. Posterior view of ditto, showing the undulations of the base and the elevation 



of the dorsal surface. 



d. Lateral view of ditto, showing the great elevation of the anterior half of the test, 



and the eccentricity of the vertex. 



e. Tubercles from the base, with their hexagonal areas. 



2 a. Upper surface of another specimen in my collection. 



h. Two inter-ambulacral plates, a portion of the poriferous zones, and ambulacral area, 

 magnified four times. 



c. Apical disc and madreporiform tubercle, magnified. 



d. Tubercles from the upper surface, greatly magnified. 



3. Apical disc from a French specimen after M. Cotteau, showing the size and arrange- 

 ment of the plates. 



