PLATE XX. 



PSAMMECHiNi'S ciNGULATUS Clark (page 55). 



Fig. la. Upper surface of the test. 



lb. Lower surface of the test. 



Ic. Lateral view of the same. 



Id. luterambnlacral area, enlarged. 



le. Three plates of tlie same, highly magnified. 



If. Amlmlaeral area, enlarged. 



Ig. Four plntes of the same, highly magnified. 



Ih. Month opening, enlarged. 



1). Tubercle. 



144 



