PLATE VII. 



CiDARTS TEXANUS Clark (page 36). 



Fig. la. Test restored, natural size. 



Ih. View showing the arrangement of the interambnlacral plates in the vicinity 



of the apical disk, with adjacent ambulacral plates. 

 Ic. Portion of ambulacral area, enlarged. 

 Id. Interambnlacral plate, enlarged. 

 le. Tubercle, much enlarged. 



Leiocidaris hemigranosus (Shumard) (page 38). 



Fig. 2a. Interambnlacral plate. 



2b. Portion of ambulacral area, enlarged. 

 2c. Tubercles, magnified two diameters. 

 2d. Apical disk, enlarged. 

 118 



