PLATE II. 

 Cidaris tribuloides,/. J-3. 



1. Seen in profile. 



2. Seen from the actinal side. 



3. Seen from the abactinal pole. 



Arbacia punctulata,/ 4. 



4. Seen from abactinal pole. 



Toxopneustes variegatus,/ 5, 6. 



5. Seen from above. 



6. Seen in profile. 



(All Jigs, natural size.) 



