DERM AT< >I >I A I )EMA HORRIDUM. 



io 



20 mm. 



Fig. 120. I), horridum. 



ambulacral plates have retained nearly the same size as in the preceding 

 stage; they, however, are rounded off and project somewhat into the 

 actinal system, forming slight gill cuts more marked than in the preceding 

 stage. The ninth pairs of interambulacral plates have fully developed, and 

 the tenth pairs are indicated in the anterior interambulacra and the left pos- 



7.3 mm. 



15 mm. 20 mm. 



Fig. 121. D. horridum. 



