330 Reports and Proceedings — 



The species described by the author were Heliastrcea tasmaniensis, 

 sp. n., Thamnastrcea sera, sp. n., and a second species of Thamnas- 

 trcea. Both these genera are composed of reef-building corals, and 

 the species here described undoubtedly belonged to that category. 

 They required the natural conditions peculiar to Coral-reefs. The 

 author noticed the facts as to the distribution of land and water in 

 the Australian region in Lower Cainozoic times, which are revealed 

 by the deposits belonging to that age, and indicated that although 

 the insular distribution of the land may have been unfavourable to 

 the growth of Coral-reefs, the existence of a suitable sea-tempera- 

 ture in the latitude of Tasmania is insufficiently explained. A 

 single relic of the old reef-building Corals survives on the shores of 

 Tasmania in the Ecliinopora rosularia, Lam., but all the other forms 

 have died off. The coral isotherm would have to be 15° lat. south 

 of its present position to enable reefs to flourish south of Cape Howe, 

 and this could be caused only by a change in the arrangements of 

 land and sea, and in the position of the polar axis. The author 

 indicated the general arrangements of land which seemed to have 

 prevailed, and noticed that at that period and even earlier the coral 

 isotherm of 74° reached fully 25° north of its present position in the 

 portion of the globe antipodean to Tasmania ; but it would seem to 

 require more than mere geographical changes to account for the 

 existence of important reefs in western, central, and southern Europe 

 and in Tasmania synchronously. The flora underlying the marine 

 Cainozoic deposits of Victoria indicate tropical conditions, as do the 

 Echinodermata of the succeeding strata (described in the following 

 paper). The fossil plants of the Arctic regions, from the Carboni- 

 ferous to the Miocene epoch, give evidence of the existence of higher 

 temperatures and of other conditions of light than those now pre- 

 vailing ; but were the polar axis at right angles to the plane of the 

 ecliptic, and were there no greater node than at present, there would 

 be equal day and night at all points. The difficulty is to account 

 for the present position of the axis on this supposition ; but the 

 author suggested that the great subsidences of Miocene lands, the 

 formation of the southern ocean, and the vast upheavals of northern 

 areas at the close of the Miocene epoch, may have sufficed to produce 

 the present condition of things. 



2. " On the Echinodermata of the Australian Cainozoic (Tertiary) 

 Deposits." By Prof. P. Martin Duncan, M.B., RK.S., President. 



In this paper, after noticing the history of our knowledge of 

 Australian Tertiary Echinida, the author gave a list of the species 

 at present known, amounting in all to 23, and described the fol- 

 lowing as new species : — Leiocidaris australicB, TemnecJiinus lineatus, 

 Arachnoides Loveni, A. ehngatiis, RhyncTioi^ygus dysasteroides, Echi- 

 nohrissus australicB, Holaster australice, Haretia anomcda, Eupatagus 

 rotundus, and E. Lauhei. The author remarked upon the characters 

 and synonymy of the previously known species, his most important 

 statement being that the so-called genus Memipatagus is in reality 

 identical with the recent genus Lovenia, Gray, as clearly shown by 

 fine specimens in his possession. The most marked genera of the 



