SEA LILIES, STARFISHES, ETC.—CLARK. 39 
Genus MEDIASTER, Stimpson. 
MEDIASTER AUSTRALIENSIS,! sp. nov. 
(Plate ix., fig. 1-2; Fig. 1-3.) 
R=82 mm.; r=30 mm.; R=2.67r. Br=30 mm.; 
R=2.67 br. Br at middle of ray=11 mm. ; at tip, 2.3 mm. 
In the largest specimen, R=100 and r=40 mm. Disk large 
and flat ; arms wide at base but tapering rapidly to a nearly 
cylindrical tip. Abactinal plates tabulate, more or less paxilli- 
form (Fig. 1) especially at centre of disk and along midradial 
Rig, LxlO.. Fig. 2.x10, 
Fig. 3.x10. 
lines ; small and numerous; the largest and most paxilli- 
form are crowned with a marginal series of 12-15 angular, 
blunt spinelets or coarse granules and within this circle 
3-8 similar but smaller granules; the smallest and least 
paxilliform plates adjoin the superomarginals in the 
interradial areas and are crowned with a little group 
of 3-5 angular granules; the coarseness or fineness 
of the paxillar granules shows great diversity in different 
individuals and even in different parts of the same disk ; thus 
in one specimen, plates proximal to the madreporite carry 
10-20 coarse, well-spaced granules, while plates of the same 
size, distal to the madreporite, carry 25-40 smaller, more 
rounded and more crowded granules. Occasionally one or 
more of the granules is replaced by a 2-jawed pedicellaria ; in 
the holotype, these pedicellariz are very numerous and are so 
much higher than the granules (about twice as high), that they 
are quite conspicuous ; they are also quite symmetrical and 
frequently entirely replace the granules on the top of the 
plate (Fig.2); in other specimens, pedicellarie are exceedingly 
rare, while in still others, though common, they are small and 
1. Australia+ensis, expressing locality. 
