PLATE XVIII. 
Paleopneustea hystrix A. Aa. 
Fi". 1. Left balf of test covered with spines, seen from above, natural size. 
Fig. 2. Eight half of test from above, denuded. 
Fig. 3. Abaiitinal system (|). 
Fig. 4. Same as Fig. 1, seen from actinal side, covered with spines. 
Fig. 5. Same as Fig. 2, seen from aotinal side, denuded. 
Fig. 6. Actinostome (f), seen from actinal side. 
Fig. 7. Same as Fig. 6, seen from the interior. 
Fig. 8. Anal system (f). 
