CIDARID^. 



13 



the right anterior interambulacrum, the actinal plates were 1, 1 in all the 

 interambnlacral areas, the plates of the right zones being the smallest in all 

 cases, except in the odd interambulacrum. In the stage of 10 mm. the 

 second plate of the right ambulacral zone has reached the actinal system, 

 and only a small part of the largest of the first plates has not been 



21 mm. 



Fig. 33. Pobocidabis Cobosi. 



resorbed, the interambnlacral plates having increased also from six to 

 seven plates. In the larger stage, having nineteen pairs of ambulacral 

 plates, the sixth pairs of interambulacral plates barely indicated in the 

 preceding stage, have become fully grown plates, and the seventh pairs 

 are indicated. 



In a specimen of 18 mm., Fig. 32, only a small triangular part of the 

 first plate remains in the left lateral interambulacra, and the second plates 



