J. W. Gregory — Australian Echinoidea. 489 



The genus Hemiaster has not been hitherto described from 

 Australia, but a species is known from New Zealand. H. pJane- 

 declivis belongs, however, to a very different group to this H. posita, 

 Hutton, 1 which has a cordate, inflated test, with the pores on the 

 inner side of the postero-lateral ambulacra obliterated near the 

 apical area. Moreover, the latter species is said in the diagnosis to 

 have neither subanal nor peripetalous fasciole. If this be correct, 

 the species is not a Hemiaster, but must be transferred to the genus 

 Epiaster. 



The generic determination of this Echinoid may be considered 

 doubtful by the French palaeontologists who separate from Hemi- 

 aster all the Cainozoic forms. But apart from the disputed question 

 of the validity of the new genera to which these species are referred, 

 the affinities of H. planedeclivis are so distinctly with the Cretaceous 

 group that it must be regarded as a true typical Hemiaster. 



III. —From Nullarbor Plains. 



During the exploration of the country between Port Augusta and 

 Eucla, 2 a few Echinoidea were collected from the Nullarbor lime- 

 stone ; these have also been presented to the British Museum (Nat. 

 Hist.) by H. Y. L. Brown, Esq. At Tallowan Well in the Fowler's 

 Bay district an Echinolampas, sp., and some fragments probably 

 referable to Eupatagus were collected. The other specimens were 

 without definite locality : they are Echinus wooclsi, Laube, and 

 Lovenia forbesi (Woods and Dune). 



IV. — The Affinities of the Echinoid Fauna. 



Many attempts have been made to classify the Australian Cainozoic 

 deposits, and to establish definite correlations of the beds of the 

 various localities with each other, and with the European formations; 

 no very definite classification has, however, as yet been agreed upon. 

 But an examination of the faunal lists clearly shows that various 

 horizons are represented, and until the relations of these are at least 

 approximately known, no definite conclusions as to the affinities of 

 the fauna can be established. 



As Mr. Woodward's collection was made at a new locality, it is 

 necessary to consider the relations of the fauna to those from other 

 places in South Australia and Victoria. Of the five recognizable species 

 three are new, but the other two are well-marked forms ; they suggest 

 that the beds belong to the lowest of the three divisions into which 

 it seems generally agreed that these Australian Cainozoic deposits 

 can be divided. As to the terms to be applied to these divisions, 

 however, opinions differ greatly. The banks of the Murray River 

 exhibit the longest continuous sections, and afford the best oppor- 



1 F. "W. Hutton, Cat. Tert. Mollusca and Echinodermata of New Zealand, New 

 Zealand Geol. Surv., Miscell. Publications, No. IX. 1873, p. 42. Hector, Cat. of 

 Geol. Exhibits, New Zealand Court, India and Colonies Exhibition, London, 1886, 

 p. 54, fig. 1. 



2 H. Y. L. Brown, "Eeport of Country passed over from Port Augusta to 

 Eucla," Adelaide, 1885. 



