NOTES ON A COLLECTION OF TERTIARY LIMESTONES. 
There is no doubt of the relationship of the two specimens 
figured, since all the chief characters are common to both. 
Observations.— Mopsea hamiltoni has been lately described by Mr. 
J. A. Thomson, from the greensands accompanying the limestones 
at Kakanui, New Zealand. Mr. Thomson remarks on the apparent 
identity of Duncan’s New Zealand example, Isis sp.* * * § , with the type 
above referred to, and the writer had come to the same conclusion 
regarding these, and also the Cape Otway specimens figured by 
Duncan, f prior to seeing Mr. Hamilton’s paper. The fossils, how- 
ever, belong to the genus Mopsea and not to Isis, as will be seen on 
comparing the structure of the joints with those of the species of 
Mopsea still found living round the Australian coast. Duncan’s 
remarks upon the affinities of the fossils did not clear the ground 
for later students, for, in following Ehrenberg, he says, “It is this 
branching from the calcareous body which distinguishes the genus 
Isis from Mopsea, in which the branching starts from the horny 
substance ( loc . cit., p. 673). In point of fact, the typical Mopsea 
encrinula, to which our species is allied, shows the branching to 
take place on the calcareous internodes by the formation of a horny 
node, in some cases, however, so close to the node as to appear to 
start from it, when in reality it is attached to the calcareous joint 
(see also Wright and Studer, Chall. Rep. on Alcyonaria, p. 40). 
The above species is distinct from Tenison Woods’ Isis dactyla,% 
in having finer lateral striations and concentrically lineate condyles. 
Isis melitensis of Gfoklfuss,§ is more nearly related to I. dactyla in 
having fine and numerous lateral furrows; whilst the internodal 
faces are acutely conoidal and devoid of radial grooves. Goldfuss’ 
species was found in the Pliocene of Sicily and Piedmont. 
The above species was found in the polyzoal rock of the Seal 
River outcrop. 
ECHINODERMATA. 
Cidaris ( Leiocidaris ) cf. australiae, Duncan sp. 
Leiocidaris australiae, Duncan, 1877, Quart. Journ. Geol. Soc., 
Vol. XXXIII., p. 45, pi. iii., figs. 1, 2. 
There is a somewhat Worn fragment of the test of a cidarid in 
the present series. It shows a portion of the interambulacral area 
with two primary tubercles and a line of ambulacral pores. Only 
the one species above mentioned has been recorded from our Ter- 
tiaries, and the present specimen, so far as the fragment shows, is 
probably referable to it. It was first described from the Cape 
* 9 uart - Journ ; «eol Soc vol . xxxi., 1875, p. 075, pi. xxxviiiB., figs. 1 i a 
t Loc. supra cit p. bi 4, pi. xxxviiia., figs. 5, 5 a. 
iv - “ d - *• i— i. 
§ Petrefacta Germaniae, 1826-1833, vol. i., p. 20, pi. vii., fig. 17. 
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