Plate 73. 

 1-5. Urechinus giganteus A. Ag. ; Station 3431. 



1. Actinal system and surrounding plates of specimen 80 mm. in length, showing resorp- 



tion of miliaries in the posterior ambulacra. 



2. Part of test of specimen 80 mm. in length, facing the right posterior interambulacrooj, 



showing resorption of tubercles. 



3. Part of test of same specimen, near ambitus, facing the right anterior ambulacrum. 



4. The third plate from the actinostome of the left posterior interambulacrum, to show 



resorption of tubercles. 



5. Anal system of same. 



