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to the base of the corallum. In a young example lately collected, 
about two-thirds of the upper portion of the fossil has been worn 
away by fossilization, and at the bottom there is still a prominent 
columella. 
The coste are continuous with the septa, and thus vary in 
number exactly as these do. Including the quaternaries the 
total number of costz is normally 36, but in the example men- 
tioned with four extra tertiary septa, 44 separate coste were 
counted at the upper margin of the wall, there being a quater- 
nary in every interspace of the other cycles. The primaries are 
distinct and free right to the base; the tertiaries unite with the 
secondaries at varying heights on the wall from about two-thirds. 
below the summit to quite close to the base. These three orders. 
of cost are stout and subequal in size. the primaries becoming, 
perhaps, slightly the stouter towards the base. The coste of the 
fourth order are always weli developed, and about half as thick 
as the others; they meet either the secondaries or the tertiaries. 
at heights on the wall which vary considerably in the several 
systems. The intercostal spaces, which towards the upper margin 
of the corallum equal the costz, are crossed by thin transverse: 
bars, between which there is a series of regular pores similar to 
those in 7’. fenestratus ; they are, of course, most conspicuous in 
the upper part of the corallum, where the intercostal spaces are 
widest. In the young example referred to above with worn and 
excavated calice, the pores are visible on the inner as well as the 
outer surface of the wall. Towards the margin of the calice 
also in most examples the complete perforation of the wall is. 
plainly seen. 
Altitude, 5 mm.; greatest diameter of corallum, 4 mm. ;. 
diameter of calice, 3 mm. 
Locality.—Tolerably abundant in Miocene beds at Mississipi 
Creek, Gippsland Lakes area. Twelve examples. The species. 
name is in compliment to Mr. Donald Clark, from whom I 
received my first specimen. 
EXPLANATION OF PLATES. 
Puate IT. 
1. Flabellum Gippslandicum—a, corallum, nat. size ; ), calice, 3 diam. 
2. Flabellum fastigatum—a, corallum, nat. size; b, calice, 2 diam. 
3. Placotrochus corniculatus—a, corallum, 1°5 diam.; 6, calice, 4 diam. 
4. Paracyathus Tasmanicus—a, corallum, 2°5 diam.; b, calice, 5 diam. 
Puate Ill. 
1. Stephanotrochus Tatei—a, corallum, 2diam.; b, base, 2 diam.; c, calice, 
3 diam. 
2. Trematotrochus Clarkvi—a, corallum, 6 diam.; }, calic e, 10 diam. 
3. Flabellum curtum—a, corallum, 2 diam.; 6, calice, 3 diam., showing 
three systems. 
