THE CAINOZOIC CIDARIDAE OF AUSTRALIA. 
of shaft near tip, 4 mm. Complete spine with shorter thorns, length 87 mm. ; 
width at ring, 9 mm. ; width of shaft near tip, 4.5 mm. Fragmentary flattened 
spine showing terminal, lower beds, Aldinga (Tate Coll.) ; thickness, 3.25 mm. ; 
minimum width. 6.5 mm. ; maximum width, 9.25 mm. 
Observations. — Prionocidaris scoparia has the narrow inter- 
ambulacrum found in recent species. In young specimens the 
median area of the interambulacrum is very small ; it becomes 
larger as the test grows, but even in adults it is relatively 
narrow. In a young test from Aldinga primary tubercles are 
partially crenulated. Lyman Clark states that the inter- 
ambulacra in recent species are not densely clothed with 
miliaries. 
Though fragments of tests of P. scoparia are difficult to 
distinguish from those of Phyllacanthus duncani, the latter 
species has a wider interambulacral median area, more sunken 
scrobicules, and pores of a pair more widely separated. So far 
we have not seen both species from the one horizon, though in 
a few cases both occur in the one locality. 
Localities. — Victoria — Castle Cove, Aire Coast, Wilkinson's locality No. 
5AW. Allotment 14, Parish of Wataepoolan ("C.P.C.”). Waurn Ponds 
(“H„” “C.”). Nelson (“H.”). South Australia Aldinga, lower beds; 
S., "C.” ; paratypes, 4 spines, C. and 4 fragmentary spines, S. ; svntype and 
paratype (spine), Tate Coll. Knight’s Railway Siding Quarry, Mt. Gambier 
(“C.,” “F.C.” ; syntype, N.M.). Morgan, lower beds (“C.,” a young 
specimen ?). 
Range. — Upper Oligocene to Miocene. 
Genus GONIOCIDARIS L. Agassiz and Desor 1846. 
Living species of Goniocidaris arc confined to Australasian 
seas ; G. tubaria is mainly a littoral form, but G. austral iae has 
been found down to 470 metres. The genus is well represented 
in our Cainozoic. rocks. The main distinguishing characters are 
the conspicuous bare sunken areas of the ambulacrum and of the 
interambulacrum, and the pits in the latter. Pores are non- 
conjugate (Clark, 1925, and Mortensen, 1928). In other parts 
of the world various fossils have been referred to this genus, 
but the only examples which, we believe, may belong to it 
occur in the Miocene of India and in the Miocene and Pliocene 
of the Persian Gulf. 
Goniocidaris prunispinosa Chapman and Cudmore. 
Plate XIII, figs. 12-14. 
Goniocidaris prunispinosa Chapman and Cudmore, in Chapman, 1928, 
p. 90. 
The following description is amplified and emended from our preliminary 
description. 
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