102 



PANAMIC DEEP SEA ECHINI. 



large scrobicular areas on the outer edge of the plates in Ph. panamense, 

 while there are but five and six in Ph. hispidum. A similar difference in 

 the number of the miliaries exists on the abactinal side, Fig. 145. The 

 interambulacral plates are also more elongated in Ph. panamense ; there are 

 nineteen and twenty plates from the ambitus to the abactinal system, having 



• Pm 



140 mm. 

 Fl(i. 145. PlIORMOSOMA PANAMENSE. 



140 mm frgt. 



Fro. 146. Phormosoma panamense. 



a primary tubercle with a small scrobicular area on alternate plates, and 

 with a few secondaries near the outer and inner edges of the plates, while 

 there are only fifteen and fourteen in a specimen of Ph. hispidum of 

 140 mm. In Ph. hispidum there are no large primaries on the abactinal 

 side, but two to three large secondaries on each interambulacral plate. 

 On the actinal side the ambulacral area is marked for the large size of 



