77 
or more in one direction. The genus, as an Australian fossil, has been 
previously recorded, with some observations, by R. Etheridge, jun. 1 , from 
the Carboniferous oolitic limestones of Stanwell, Queensland. 
Locality and Horizon .—Thomson River, Gippsland. Silurian (Yer- 
ingian). 
Genus Monticulipora, D’Orbigny. 
Sub-Genus MONOTRYPA, Nicholson. 
Monotrypa sp. Plate IV.; fig. 8. 
Observations .—An example of this sub-genus has already been 
found in a Victorian limestone bv Mr. W. S. Dun 2 , the locality, near Mans¬ 
field, being in all probability on the same horizon as the present series 
from Tyers River. So far as the present example goes, we have only an 
approximately transverse section of the fossil, so that further than stating 
that it agrees in thlat respect with Mr. Dun’s fossil, we cannot venture. 
In our specimen, where the corallites are cut through somewhat obliquely, 
traces of thin, distant diaphragms are seen. 
Locality and Horizon .—Tyers River, Gippsland. Silurian (Yeringian). 
Class ECH 1 NOIDEA. 
Genus (?) Palceechinus (Scouter), McCoy. 
Spines of a palseechinoid, probably referable to Palceechinus. Plate 
IV,. fig. 9 ; pi. VII., fig. 16. 
The spines here provisionally referred to Palceechinus are somewhat 
abundant in the Tyers River limestone. Those shown in the accompanying 
photographs are sections which pass through the spines both transversely 
and longitudinally. The spines are a little variable in size; they are acicular 
and of medium length, and generally resemble those which have been fig¬ 
ured as occurring with the test of Palceechinus. In the diagnosis of this 
genus Duncan 3 says, “spines small, acicular, short.” The peculiar structure 
seen in the longitudinal section (PI. XI., fig. 16) is brought out in places 
by an infiltration of dark limonitic material into the more cellular areas 
of the spine. This gives a somewhat analogous appearance to that ob¬ 
served by the writer in certain echinoid spines resembling Hemifedina , 
found in Lower Cretaceous limestones in the South of England, in which 
the spines had been invaded by glauconite 4 . The transverse sections of 
some of the spines seen in the thin slices of the Tyers River limestone 
have a fimbriated periphery, which indicates that the spine was finely 
and closely grooved down its length. A similar spine is figured by W. 
H. Bailey 5 , as occurring with P alee echinus elegans, McCoy 6 , and the 
length there given coincides exactly with! ours. 
The first account of the occurrence of the genus Palceechinus in Australia 
was given by Mr. J. Mitchell 7 , who described an imperfect test from the 
Middle Trilo-bite bed (Silurian) o‘f Bowning, New South Wales. 
In the Melbourne National Museum collection there is a single interam- 
bulacral plate of Palceechinus , which was generically determined by McCoy, 
This specimen differs in its ornamentation from the plates figured by 
Mitchell, in having a finer tuberculated surface (so far as can be seen from 
1 Geol. Surv. Queensland, Bull. No. 19,1900 p. 8. 
2 Proc. K. Soc. Viet., vol. X . n. s., 1898, pt II., p 89. 
3 Journ. Linn. Soc. Lond., Zo L, vol. XXIII., 1891, p. 14. 
4 Quart. Journ. Geol. Soc., vol. L , 1894, p 680 . 
5 Journ. R Geol. Soc. Ireland, vol. I., 1867 (1864-7), pi. IV.. fig. E. 
6 This species is now referred to the trenus Rhcechinus, Keeping, which has only one row of pairs of pores 
on each si ( e of an ambulacrum. The genus is essentiallv Carboniferous, as known at present. 
’ Proc. Lain. Soc. N.S.W., vol. XXII., pt. 2., 1897, p 258. 
