10 



PANAMIC DEEP SEA ECHINI. 



sixth pairs of interambiilacral plates have become fully developed, and 

 the seventh are indicated in all the interambulacral areas except the left 

 posterior one. The first pairs of interambulacral plates are still in contact 

 with the actinal system, although all greatly diminished in size since the 

 preceding stage. 



In a spuciineii of 2o mm., Fig. 28, the first pairs of interambulacral plates 

 are adjacent to the actinal system only in the left posterior interambu- 



30 mm. 

 FlO. 29. DOROCIDARIS PAXAMEXSIS. 



lacrum ; in all the other interambulacra one of the second plates has 

 reached the actinal system, and the first plate left is reduced to a mere 

 threa<l. The sixth and seventh interambulacral pairs of plates are 

 now fully developed, and the eighth is indicated in the left lateral 

 interambulacra. 



