428 



PROF. P. M. DUNCAN OJST ECHINOIDEA 



which numbers (counting three deep-sea forms) at least thirty-one 

 genera*. Even such common Australian genera as Salmacis, Arnbly- 

 pneustes, ffolopneust.es, Breynia, and Echinocardium are not repre- 

 sented in the list of fossil species. In this slight relation to the 

 recent fauna the Australian Tertiary Echinoidea resemble the fauna 

 of the Tertiaries of Sind, Kach, Kattywar, and the Mekran coast ; 

 in both instances the percentage-method of classifying Tertiary 

 deposits will fail, and the explanation must refer to the great 

 changes which occurred along all the coast-lines of that part of the 

 world at the close of the Pliocene age. 



As a whole, the grouping of the genera of the Australian Tertiary 

 Echinoidea is a mixture, and it is characterized by the presence of 

 genera which commenced in the Mesozoic ages, of a majority of 

 genera which began in the Tertiary ages and have lasted on, and of 

 a few characteristic Tertiary genera. There are three genera special 

 to the fauna. 



But when the genera which began in the Mesozoic age are con- 

 sidered, it will be found that four of them are represented by living 

 species, for instance Oidaris, Salenia, Echinobrissus, and Catopygus. 

 Micraster lasted into the ISTummulitic of Sind, and the Australian 

 species is the latest ; and the Holasters are recognized, only in 

 Australia, as Tertiary forms and not early Tertiary. 



The essentially Tertiary species are those of the genera Pygo- 

 rhynchus and Pericosmus. The genera which arose during the 

 Tertiary ages and are still represented by species are Echinolampas, 

 Maretia, Lovenia, Euspatangus, Schizaster, Clypeaster, Psammechinus, 

 and Goniocidaris. The special genera are Ortholophus, Paradocc- 

 ecJiinus, and Megcdaster, and the first two have very Sindian 

 (Eocene) alliances. 



The greatest interest of the fauna is, of course, centered in the 

 Holasters, and every student of the recent fauna will recognize 

 their importance in reference to the abyssal Echinoidea with 

 apetalous and flush paired ambulacra, and which present such a 

 curious mixture of antique and very modern structures. But 

 instead of allying the abyssal Ananchytyoid-looking forms, classified 

 under the genera Homolampas, A. Ag., Genicopatagus, A. Ag., 

 Cystechinus, A. Ag., and Urechinus, A. Ag., with the Holasters and 

 Ananchytes of the Chalk, it will be necessary to consider them in 

 reference to the Holasters of the later Tertiaries of Australia. Just 

 as it is now necessary to consider the recent Salenice as the modified 

 descendants of the Tertiary species, so it is obligatory to believe 

 that the very degraded and yet in some points very anciently 

 structured abyssal species of the genera mentioned above are the 

 modified and degenerate successors of Tertiary predecessors. 



There are no species which are common to this Australian fauna and 

 that of the Indian Tertiaries, and the alliance with the European 

 faunas is slight indeed. The large species of Pericosmus recall the 

 forms from the Javan Tertiary deposits, but the species of the two 

 localities are not the same. 



* Bamsay, Catal. Echin. Austr. Mus. pt. i. (1885). 



