10 



PANAMIC DEEP SKA ECHINI. 



sixth pairs of interambulacral 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 specimen of 25 mm.. Fig. 28, the first pairs of interambulacral plate- 

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



30 mm. 

 Fl(i. '.".I. DORO< [DABIS PANAM1 NSIS. 



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 

 thread. The sixth and seventh interambulacral pairs of plates are 

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

 interambulacra. 



