GENEEA AND GEOTJPS Or THE ECHINOIDEA. 101 



Peristome small, almost without cuts. 

 Fossil. Australian Tertiaries (Mordialloc). 



Genus Paeadoxechinus, Lauhe, 1869, Sitzungsh. d. kais. AJcad. 

 d. Wiss. Wien, Bd. lix. p, 186, fig. 2. {Amended.) 



Syn. Coptechinus, Cotteau, 1883. 



Test small, depressed, much broader than high, tumid at the 

 ambitus and slightly pentagonal in marginal outline, flat actinally. 

 Epistroma well developed. 



Apical system wanting, but was large, wide, and circular. 



Interradia moderately broad, with a vertical row of primary 

 tubercles near the ambulacra ; the successive tubercles are united, 

 by a narrow fillet or ridge on which are two rows of small 

 secondaries or large granules, and there is a zigzag of fillets com- 

 posed of double rows of similar secondaries or granules between 

 the opposite vertical rows of primary tubercles ; moreover a 

 zigzag exists, of corresponding structure, between the interradial 

 and the ambulacral tubercles. 



The ambulacral primaries are in two rows placed vertically, 

 and there is a zigzag of raised fillets between them as in the inter- 

 radia. The width of the ambulacra is very slightly less than that 

 of the interradia, and the primary tubercles of both areas are sub- 

 equal, smooth and non-crenulated. The test is deep and flat be- 

 tween the fillets, and the pairs of pores, three to a plate, in the am- 

 bulacra are on the deep part of the test and more or less in grooves. 



The peristome is pentagonal, and the branchial cuts are slight. 



Fossil. Miocene of Murray Cliffs, S. Australia. 



Laube described one species, P. novus, and the dimensions of 

 the specimen are important. Height 6"5 millim., diameter 

 13 millim., diameter of the apical scar 7 millim., diameter of 

 peristome 4 millim. It is evident that the apical system was 

 large, and from Laube' s figure it would appear that all the radials 

 reached between the basals to the periproct. 



Cotteau has defined a genus Coptechinus, 1883, "Ech. nouv. ou 

 peu connus," Bull, de la Soc. Zool. de la France, vol. viii. p. 456, 

 from the Miocene of France, and it is synonymous with Para- 

 doxecMmis, Laube. 



Genus Echinoctphus, Cotteau, 1859, Ech. du Dept. de la SartTie^ 

 p. 226, pi. xxxis. bis. fig. 6 ; 1862-67, Fal. Franc^. Terr. Cr'ei. 



