18 NEW AUSTRALIAN ECHINOID 
Brochoplewrus australiae sp. nov. 
Fig. 1. 
Height, 4-0 mm. Horizontal diameter, 9-0 mm. Peristome lost 
from holotype. 
Apical system lost from the Australian specimens, but the New 
Zealand species, which is very similar, indicates the type of apical 
system normal for the genus, all the plates being exsert, to form 
the dieyelie arrangement. 
Ambulacral plates, 10 (or 11?) in each series. Interambulacral 
plates, 9 (or 10?) in each series. 
Interambulaeral sculpture. — Each primary tubercle is sur- 
rounded by a radiating system of ca. 10 to 12 raised ridges, some 
of which anastomose with ridges from neighbouring primary 
tubercles. In general, 2 or 3 of the ridges link each tubercle with 
its immediate neighbour above as also below. The laterally placed 
ridges branch and end blindly. All the ridges are characterized 
by carrying several secondary tubercles, and the blind termina- 
tions of the ridges frequently carry secondary tubercles. Along 
the mid-zone of the interamb there is an irregular, sinuous ridge, 
broader and more flattened than the radiating ridges, and this too 
carries scattered secondary tubercles. Between the mesh-work 
formed by all these ridges, the intervening surface of the test is 
perfectly smooth. 
Ambulacral sculpture. — Each pore-pair lies within a de- 
pressed oval area, with distinct horizontal ridges separating each 
depressed region from its neighbours above and below. The 
ambulacral mid-zone is traversed by more or less horizontal 
ridges, each carrying several secondary tubercles. Of these ridges, 
approximately every alternate one traverses the mid-zone from 
side to side, while the intervening ridges run only about half or 
two-thirds of the distance in each case. The primary tubercles 
form a vertical series on either side of the amb, between the mid- 
zone and the poriferous zone, and are situated on a well-marked 
sinuous vertical ridge. This ridge communicates on the outer side 
with the horizontal ridges separating the pore-pairs, and on the 
inner side with the horizontal ridges which cross the mid-zone. 
The test between the mesh-work of ridges is quite smooth. 
Holotype. Specimen 4687 in the National Museum of Victoria. 
Locality. Lower Murray cliffs, South Australia. 
Horizon. This is stated to be Janjukian (1.е., Upper Oligocene 
or Lower Miocene). 
