200 
marginal plates transversely elongated, slightly supra-marginal in 
position, and thus partially visible dorsally, diminishing very 
gradually in size towards the apices of the rays ; interbrachial 
marginals apparently two in number, much larger than the others, 
and generally triangular in shape ; oral plates not distinctly 
visible, but apparently lanceolate. 
Obs. — This elegant little Star-fish, the first of its genus described 
from Australian rocks, in form and proportions generally resembles 
Palceaster matutina , Hall,* * * * from the Trenton Limestone, but 
Hall gives very few particulars of its actinial surface. From P. 
Shcefferi , Hall,f from the Hudson River Group, and P, eucharis , 
Hall,J characteristic of the Hamilton Group, our species is sepa- 
rated on the one hand by the much more transverse form of its 
ambulacral plates, and proportionately wider ambulacral avenues; 
and on the other by its much smaller size. The latter feature 
will likewise serve as a point of separation from P. granulosus , 
Hall,§ also a fossil of the Hudson. 
Amongst other American species, to which P. meridionalis is 
far more nearly allied than to the British, P. niagarensis , Hall, || 
is easily distinguished by its large boss-like marginal plates. P. 
antiquatus , Locke, ** * * §§ and P. exculptus, Miller, f fare much too large 
to need comparison. In P. Dyeri , Meek, J J are similar transverse 
ambulacral plates to those of our species, but the adambulacral 
and marginal plates are quite different to those of the latter. It 
is hardly necessary to institute a comparison with such a well- 
marked form as Pal< vaster Jamesi , Dana,§$ for in this species there 
are enormously developed adambulacral plates, or at least, what 
appear to be so. 
It is unnecessary to compare P. meridionalis with any of the 
so-called British Palseasters, for the Star-fish so far referred to the 
genus by English authors, do not, in the opinion of the Writer, 
belong to that genus, with one exception. The latter isP. caractaci , 
Salter, and this unfortunately is a MS. name. It has already 
been shown by Prof. H. A. Nicholson and the Writer, that 
Palceaster as understood by Salter, and those who followed him 
is not Palcmster , Hall, and we therefore instituted a new genus 
for the reception of the British species. |||| 
Loe. and Horizon. — Moonee Ponds, near Melbourne, Victoria. 
Coll. — Australian Museum. 
* Twentieth Ann. Report State Cab. Nat. Hist. Univ. N. York, 1867, 
p. 283, t. 9, f. 2. 
f Ibid, p. 284, t. 9. f. 1. X Ibid, p. 287, t. 9, f. 3 and 4. § Ibid, p. 285. 
|| Pal. N. York, 1852, ii., p. 247, t. 51, f. 21. 
## p r0 c. Acad. Nat. Sci* Pkiladel., 1846, iii., p. 33. 
ft Journ. Cincinnati Nat. Hist. Soc., 1881, iv., p. 69, t. 1, f. 1. 
XX Ohio Geol. Report, Pal. I., Pt. ii., p. 58, t. 4, f. 2 — 2/. 
§§ Palasterina , Man. Geology, 1875, 2nd Edit. p. 205, f. 375 ; Meek gives 
a good figure of this. Loo. cit ., t. 4, f. 4. 
1111 Mon. Sil. Foss. Girvan in Ayrshire, 1880, Pt. 3, p. 318. 
