62 



P. M. DUNCAN ON THE ECHINODEKMATA OE THE 



close to the notch of the anterior ambulacrum. The posterior lip is 

 sharp and slightly projecting. The tuberculation is very small. 

 Fascioles are not apparent. 



Fig. 1. — Megalaster comjpressus, abactinal surface, one half the 



natural size. 



Megalaster compresses, sp. nov. (woodcut, fig. 1). 



The test is comparatively flat ; and there is a marked depression 

 behind the abactinal area and between the posterior pair of ambu- 

 lacra. The antero-lateral ambulacra are slightly longer than the 

 posterior, and in both sets the pores are very small near the apical 

 system. The poriferous zones have the external pores elongate, and 

 very few pores exist beyond the petals. The ocular pores are nearly 

 as large as the generative. 



Length of test 4| inches, breadth 4^ inches, height 2 inches. 



Locality. — Banks of the Murray. 



IV. The Genera of Echinodermata of the Australian Tertiary and 



Recent Faunas. 



Suborders and Families. 

 DESMOSTICHA. 



ClDARID^ 



Tertiary Genera. 

 Leiocidaris. 



Diadem atid^ 



Eecent Genera. 



iPhyllacanthus. 

 Goniocidaris. 

 Steph an ocidaris. 

 ( Centrostephanus. 

 \ EcMnometra. 

 1 Strongylocentrotus. 

 ( Sphcerechinus. 



