EXPLANATION OF PLATES 



Plate 1 



Craterobrisinga synaptoma 



Fig. 1. Cotype B, X5. Actinostomial ring showing distal facets of two pairs of ambulacral plates 

 (a) where two rays have been removed; i, interradial plate; m, marginals; ad, adam- 

 bulaerals. la. Actinostomial ring, viewed from above. 



2. Large variety of pedicellaria from furrow spinelet; length 0.39 mm., X200. 2a. Inside 



view of end of blade. 2b. Pedicellaria from subambulacral spine sheath, length 0.156 

 mm., X200. 



3. Mouth plates and first three pairs of adambulacrals; right side, plates of cotype A; left 



side, cotype B, X10. 3a. Type, X10. Armature of tenth adambulacral plate; 

 sheaths removed from the two subambulacrals; marginal spine on left with pedicel- 

 lariae; 36. Cotype a, X10. Tenth adambulacral showing two large subambulacral 

 spines. 3c. Cotype a, X 10. Twenty-seventh adambulacral with accompanying 

 marginal spine on left. 3d. Cotype c, X10. A suboral spine (compare with 3). 3e. 

 Cotype c, X10. First subambulacral. 



162 



