PLATE XXI. 



Paleopneustes cristatus A. Ag. 



Fig. 1. Lower extremity of the right anterior lateral ambulacrum of a specimen 150 mm. in length 

 and 85 mm. in height (\). 



Part of test across the posterior part of the same ambulacrum at the ambitus (J). 



Apical system of same (f). 



Anal system of same {[). 



Actinostome of same (Y). 



Part of test across the ambital region of the right anterior ambulacrum, to show part of the mar- 

 ginal fasciole of a specimen 85 mm. in length. 



Young Paleopneustes cristatus, seen in profile (}). 



Part of test (corresponding to Fig. (J) of same, magnified. 



Young Paleopneustes cristatus 16 mm. in length, seen from the abactiual side. 



The same as Fig. 9, seen in profile. 



The same, seen from the actinal side. • 



Apical system of same, greatly magnified. 



Actinostome of same, greatly magnified. 



Anal system of same, greatly magnified. 



