70 P. M. DUNCAN ON THE ECHTNODERMATA OF THE 



districts and seas close by was deduced from the examination of the 

 shells by Mr. Jenkins (" Austr. Tert. Corals," Quart. Journ. Geol. Soc. 

 1870, p. 318); and the vegetation of the lignites which are at the 

 base of the Cainozoic series is stated by Miiller and Etheridge to 

 indicate a more tropical climate than the present. The proof of 

 the former extension of the coral isotherm to the south of the area 

 of these Cainozoic deposits has been afforded by the presence of reef- 

 building fossil corals in the corresponding deposits of Tasmania ; and 

 thus the existence of former warmer climates and warmer sea-tracts 

 receives confirmatory evidence *. 



The geology of these Australian deposits was sufficiently described 

 from the elaborate surveys of the Victorian geologists in the essay 

 on the fossil Madreporaria ; and it is therefore not necessary to re- 

 introduce the subject. But it is advisable to remember that very 

 considerable physical changes have occurred since the deposition of 

 the strata containing the Madreporarian and Echinodermal faunas, 

 although some of the fossils are so very recent-looking. A vast 

 outflow of basalt covered these Lower Cainozoics; and an upheaval 

 took place of the coast-line of some hundreds of feet. Then the 

 upper or gold-drifts collected on the basalt or on the strata where 

 uncovered, they being the results of subaerial denudation. A 

 second basaltic outflow covered these ; and the final elevation of the 

 coast-line followed, the marine Cainozoics being found up to 600 

 feet. Since then the rivers have cut valleys through these deposits, 

 and the alluvium has collected in which and in contemporaneous 

 caves the remarkable fossil Marsupial fauna has been preserved — 

 a relic of the remote past foreshadowing the present fauna. Since 

 then the climate has changed, and the coral isotherm is now 

 many degrees to the north ; and probably since the lifetime of the 

 Echini which form the subject of this essay, the worldwide eleva- 

 tions and subsidences which terminated the Miocene have occurred. 



EXPLANATION OF THE PLATES. 



Plate III. 



Fig. 1. Cidaris (Leiocidaris) austrcdice, sp. n., fragment, showing half an am- 

 bulacrum, natural size. 



2. Part of the same, enlarged, showing an interambulacral plate, and 



half the corresponding part of the ambulacrum. 



3. Tcmnechinus lineatus, sp. n., side view, natural size. 



4. The same, abactinal surface, wanting the apical system, natural size. 



5. Portion of the same, enlarged. 



6. Aracknoides Loveni, sp. n., abactinal surface, natural size. 



7. The same, an ambulacrum, three times natural size. 



8. Aracknoides elongatus, sp. n., side view of test, natural size. 



9. Ehynckopygus dysasteroides, sp. n., side view of test, natural size. 



10. The same, apical system, enlarged. 



11. Echinobrissus australice, sp. n., abactinal surface, natural size. 



12. Holaster austrcdics, sp. n., side view of test, natural size. 



* P. M. Duncan, Quart. Journ. Geol. Soc. vol. xxxii, p. 345. 



