1 



PLATE XXXVII. 



Pygurus Costatus, Wright. 

 From the Coralline Oolite. 



1 a. Pygurus Costatus, Wright, p. 397. Upper surface, natural size. 



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



c. Posterior view, showing the flatness of the base and the extreme depression of the 



upper surface. 



d. Two inter- ambulacral plates, poriferous zones, and ambulacral area, magnified three 



times. 



e. Phylloidal expansion of the ambulacral area near the mouth- opening, showing the 



crowding together of the pores in this region, magnified three times. 

 /. One of the lip-like processes of the mammillated, oval lobes which project over the 

 border of the peristome, magnified twice. 



