CASSIDULID.5i:. 



liu 



original suture is still visible in Fig. 3, Plate 64 ; even in this young stage 

 the effect of the thrust of the coronal plates on the actinal plates is visible 

 in the low ridge surrounding the actinal system (PI. 64, fig. 2). 



a m t 



inside. 



Fig. 153. Rhynchopygus carib^arum. 



outside. 



Fig. '[M. Rhynch. carib.earim. 



Afteb Lov£n. 



In Rhynchopygus, Figs. 153, 154, the primordial plates are all actinal, 

 but elongate and much narrower than in Echinolampas, Fig. 155. In 

 Neolampas, Fig. 156, the primordial plate of the odd ambulacrum is still 

 more drawn out by the crowding of the adjoining plates of the posterior 

 lateral ambulacra. a m a 



Fig. 155. Echinolampas depkbssa. Fig. 156. Neolampas rostellata. 



The abactinal systems of Echinolampas, Conolampas, Neoiampae, Rhyn- 

 chopygus, and Echinoneus are very similar. The genital openings in all 



