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. 



Q/)s. — 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. 

 Shoifferi, Hall,t from the Hudson River Group, and P, eucharis, 

 Hal], I 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,v< also a fossil of the Hudson. 



Amongst other American species, to which P. meridionalis is 

 far more nearly allied than to the British, I\ niagarensis, Hall, || 

 is easily distinguished by its large boss-like marginal plates. P. 

 antiq^iatus, Locke,**ancl P. exculptus, Miller,! fare much too large 

 to need comparison. In P. Dyeri, Meek, || 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 Pala'aster 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 witli 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 is P. caractaci, 

 Salter, and this unfortunately is a IMS. name. It has already 

 been shown by Prof. H. A. Nicholson and the Writer, tliat 

 Pala^aster as understood by Salter, and those who followed him 

 is not Palceaster, Hall, and we therefore instituted a new genus 

 for the reception of the British species. |j|| 



Loc. and Horizon. — Moonee Ponds, near Melbourne, Victoria. 



Coll. — Australian Museum. 



* Twentieth Ann. Eeport State Cab. Nat. Hist. Univ. N. York, 1867, 

 T) 28S t 9 f 2 



t Ibid, p.' 284, t. 9. f. 1. X Ibid, p. 287, t. 9, f. 3 and 4. § Ibid, p. 285. 



II Pal. N. York, 1852, ii., p. 247, t. 51, f. 21. 



** Proc. Acad. Nat. Sci. Philadel., 1846, iii., p. 33. 



tt Journ. Cincinnati Nat. Hist. Soc, 1881, iv., p. 69, t. 1, f. 1. 



Xt Ohio Geol. Eeport, Pal. I., Pt. ii., p. 58, t. 4, f. 2—2/. 



§§ Palasterina, Man. Geology, 1875, 2iid Edit. p. 205, f. 375 ; Meek gives 

 a good figure of this, Loc. cit., t. 4, f. 4. 



nil Hon. Sil. Foss. Girvan iu Ayrshire, 1880, Pt. 3, p. 318. 



