1076 



NOTES ON AUSTRALIAN FOSSILS, 



The authors of the ' Revision ' divide the Palreocrinoidea into 

 three suborders (1) that I will arrange synoptically as follows :— 



A. Plates of the test articulated : 2nd Sub-order Articulata. 



f Lower arm plates 

 incorporated by 

 means of interra- 

 dial plates so as to 

 form a part of the 

 calyx. Under- 

 basals frequently 

 undeveloped, etc. 



(2 families) 

 Ex. : Ichthyocrinus. 



\ 1st Sub-order Camarata. 



(10 families) 

 Ex. : Platycrinus. 



I 



B. Plates 

 of the test ] 

 united by 

 suture. 



Arms free from 

 the first radials. 

 Calyx composed 

 exclusively of 

 basals, frequently 

 underbasals, five 

 radials, five inter- 

 radials ventrally 

 located, and one 

 or two azygous 

 plates, etc. 



3rd Sub -order. 

 Inadunata. 

 I (Sub-divided.) 



Ventral covering con- 

 sisting of compara- 

 tively few pieces. 

 Disk subtegminal in- 

 stead of being ex- 

 tended into a lateral 

 sac, etc 



r 



Larviformia. 



(4 families) 

 Ex. : Cupressocrinus 



Perisome partly or 

 wholly exposed, the 

 interradial plates 

 either covering the 

 perisome, or this 

 partly covering them 

 Portions of the disk 

 penetrating the calyx 

 posteriorly by pass- -{ 

 ing out through the 

 anal opening and 

 forming either a bal- 

 loon-shaped or a tu- 

 bular sac, composed 

 of well-defined plates 

 etc. 



I 



FlSTULATA. 



(10 families) 

 Ex.: Cyathocrinus 

 Poteriocrinus 

 Tibmchiocrinus 

 Encrlnus. 



Tribrachiocriuus had been broadly compared with Cyathocrinus, 

 and its correct affinities had not been understood before they 

 were made out by the American scientists who say in the Revision 

 (2) — " The radials enclose the azygous plate proper, and an anal 

 piece as in most of the Poteriocrinidse. Tribrachiocrinus is not 



(1) 'Rev.' Part III. Sect. 1, pp. 304, 305, 313-315. 



'Rev.' Part III. Sect. 2, pp. 65, 66, 78, 81-82, 116, 117. 



(2) 'Rev.' Part III. Sect. 2, pp. 174, 175. 



