PHORMOSOMA PANAMENSE. 



103 



the outer poriferous plates, Fig. 146, which, towards the ambitus, exclude 

 several of the larger ambulacral plates from the outer edge of the am- 



FlG. 147. PHORMOSOMA PANAMENSE. 



bulacral area. The small poriferous plates form a wedge-shaped area, while 

 in Ph. hispidimi these plates form an irregularly rectangular area. The 

 row of large primary tubercles, with large scrobicular areas, consists of six 

 and eight tubercles in Ph. panamense, while there are but three and five in 



130 mm. 



Fig. 148. Phormo.«ioma panamense. 



Ph. hispidum. The miliaries are, as in the interambulacra, far more numerous 

 on the actinal ambulacral plates of Ph. panamense than in Ph. hispidum. 



