58 FIRST RECORDED OCCURRENCE OF BLASTOIDEA IN N.S. WALES, 



For convenience in comparison the characteristics of these 

 three blastoids and of the Glenwilliam specimen may be tabulated 

 as follows : — 





Troostocrinus. 



Metablastus. 



Triccelocrinus. 



Glenwilliam 

 Specimens. 



Shape of I 

 Calyx. { 



Elongated 

 fusiform. 



Elongated 

 fusiform. 



Pyramidal. 



Elongated 

 fusiform. 



Basals . . . -J 



Basal cup coni- 

 cal, forming J 

 calyx. Plates 

 convex. 



Cup conical. 

 Plates convex. 



Cup short and 



wide, excavated 



into three 



hollows. 



Cup conical. 

 Plates convex. 



Radials. -J 



Limbs very 

 short. 



Limbs shorter 

 than body. 



Limbs longer 

 than body. 



Limbs | length 

 of body. 



Ambulacra. Plates 20. 

 1 



Plates 18-60. 



Area long and 

 very narrow. 



Plates 40. 



Age 



Silurian. 



Silurian to 

 Carboniferous. 



Carboniferous. 



Carboniferous. 







N. America. 



N. America. 



N. America, 

 Queensland. 



Glenwilliam, 

 N.S.W. 



We see from above table that the genus under consideration 

 agrees most closely with Metablastus. It differs from Troosto- 

 crinus in that the sinus of the latter is short, plates twenty, 

 and age is set down as Silurian. The general shape as shown by 

 figure in Zittel (p. 195) is somewhat similar however. 



With respect to Triccelocrinus, we note the difference in shape 

 of the basal cup, as far as we can reconstruct it; the length of 

 the ambulacra is shorter in the blastoid under consideration, 

 while the figures given by Etheridge (Blastoidea, plate xix. fig. 13) 

 are very different from our specimen. Coming to Metablastus, 

 which probably is after all only a somewhat later type of Troos- 

 tocrinus, we see a close resemblance, especially with Metablastus 

 hispanicus* obtained from the Lower Devonian of Spain. The 

 latter is figured on plate 5, fig. 21, of Etheridge and Carpenter's 

 Monograph, and in general shape is similar though only about 

 one-third the length of the Australian specimen. 



p.200 E. & C. on Blastoidea. 



