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Genus Tryplasma, Lonsdale. 
Tryplasma vermiformis, Etheridge fil. (Plates XVII., Pigs. 2-3. ; XVIII., Fig. 6). 
Tryplasma vermiformis, Etheridge, jun., 1907, Mem. Geol. Surv. New 
South Wales, Pal. No. 13, p. 83, pi. XL, fig. 1 ; pi. XXIII., figs. 4, 5. 
Observations. —Some well-preserved coralla of this species are found in 
the grey limestone of Cowombat Creek, Limestone Creek (Nos. 2128-9, 2138). 
It is allied in some respects to T. lonsdalei, Eth. fil.^, and in fact might at first 
sight be mistaken for it. The differences are apparent, however, in a good 
series of examples. The distinctive features of T. vermiformis as compared 
with T. lonsdalei are, as given by Mr. Etheridge, (1) the limited number of 
septa, (2) the regularity and simplicity of the tabulae, (3) apparent absence 
of radiciform processes and fistulae. 
The distribution of the various species of Tryplasma in these Victorian 
sediments makes it appear strongly suggestive that the hydrographic condition 
of their surroundings influences the form either in direct modification or, as 
regards selective areas shown by each species. 
Occurrence. —Cowombat Creek, N.E. Gippsland. Silurian (Yeringian). 
In grey limestone (Nos. 2128, 2129, 2138). 
In New South Wales this species has been recorded from county Ash- 
burnham. 
Tryplasma dendroidea, Etheridge fil. 
Tryplasma dendroidea, Etheridge, jun., 1907, Mem. Geol. Surv. New South 
Wales. Pal. No. 13, p. 87, pi. XIV., fig. 1 ; pi. XV., fig. 5 ; pi. XVIII., figs. 
2-6 ; pi. XIX., fig. 6 ; pi. XXIL, figs. 11-15 ; pi. XXIIL, fig. 9 ; pi. XXIV., 
fig. 6 ; pi. XXVIL, figs. 3, 4. 
Observations. —Several fragmentary examples of this species, showing 
the striated epitheca, regular and complete tabulae, and general dendroid 
habit, are not uncommon. The corallites average about 12 mm. in diafneter. 
Occurrence. —In the fossiliferous limestone of Cowombat Creek (2133) ; 
in the calcareous shales of the Mitta Mitta River (2552) ; and in the fossili- 
ferous shaly mudstone of Wombat Creek (2639). In New South Wales it 
appears to be confined to the Yass District. 
Tryplasma liliiformis, Etheridge fil. (Plate XVII., Fig. 3). 
Tryplasma liliiformis, Etheridge, jun., 1907, Mem. Geol. Surv. -N. S. 
Wales, Pal. No. 13, p. 95. pi. XIV., figs, 2, 3 ; pi. XV., figs. 2-4 ; pi. XVII., 
figs. 7, 8 ; pi. XXIV., fig. 1 ; pi. XXV., fig. 8 ; pi. XXVII., figs. 1, 2. 
Observations. —It is very interesting to note the occurrence of the above 
species of Tryplasma for the first time in Victoria. The impure limestone 
of Native Dog Creek is squeezed and distorted, but the characteristic open 
and shallow cup of this coral with other distinctive structural features, may 
be clearly made out. By its appearance at a few localities only, amongst 
a large series of fossils of similar age, it evidences a local though abundant 
development due probably to suitable conditions for the growth of this 
particular form. 
Occurrence. — T. liliiformis is found in the mudstones and impure limestone 
of Native Dog Creek, Limestone Creek District (2070-3 and 2080-1) and 
in the ochreous mudstone (as casts) of Wombat Creek (2662,2666). Numerous 
examples also occur in the indurated dark-grey shales of the Gibbo River, 
Mitta Mitta River District (2674-76, 2679, 2686, 2690, 2691, 2693). 
^ Rec. Geol. Surv. N.S. Wales, vol. II., pt. 1., 1890, p. 15, pi. I. Also Mem. Geol. Surv. N.S. Wales, 
Pal. No. 13, 1907, p. 77, pi. X.; pi. XI., figs, 2-4 ; pi. XII., fig. 1; pi. XIX., fig. 4; pi. XXV., fig. 5; 
pi. XXVI., figs. 1-7. 
