Many spines of Echini have been found in the Cape-Otway and Schnapper-Point deposits; they appear to have belonged to species of the genus Goniocidaris, and possibly of Phyllacanthus and Stephanocidaris.
Note.—I have not included those forms which, although "named" by Professor McCoy, have not been described or figured by him, as it is not permitted by the common consent of palæontologists.
III. Description of the new Species.
DESMOSTICHA.
Family CIDARIDÆ.
Subfamily Goniocidaridæ, Häckel.
Genus Leiocidaris, Desor.
Leiocidaris Australlæ, sp. nov. Plate III. figs. 1 & 2.
The test is greatly and suddenly depressed towards the actinosome. The ambulacra are slightly wavy, narrow, and have four vertical rows of small miliary tubercles, the inner rows having the smallest tubercles; and the poriferous zones are sunken, the pores being conjugate, and each pair separated from its neighbours by a distinct ridge.
The interambulacral tubercles are few in number, and most are very large; the perforate mamelon is small in relation to the plain, large, conical and well-developed boss. The scrobicule is deeply sunken, elliptical, and is overhung by the scrobicular circle which slopes down to the suture, being ornamented by radiating rows of two or three very small tubercles. The median interambulacral space is sunken, and the vertical sutures of the plates are distinctly marked by a lower space, which is in a zigzag from above downwards. The upper large tubercles have a smaller scrobicular area than those in the middle of the test; and the tubercles diminish rapidly in size towards the actinosome.
Locality.—Cape Otway, No. 5 Section.
The generic diagnosis of Dorocidaris, to which genus the species has very great affinities, is given in A. Agassiz's 'Revision of the Echini,' pt. i. p. 254, and concludes with the determination, "Poriferous zone narrow, undulating, with disconnected pores." The pores in the species now under consideration are certainly conjugate; and in this they resemble Desor's genus Leiocidaris. Evidently these two genera are doubtful subgenera of Cidaris; but there are reasons for adopting them provisionally.
The resemblance of the portion of the test preserved in the soft sandstone to a corresponding part of the very variable Dorocidaris papillata of the Atlantic, Florida sea, and the Mediterranean is very remarkable; but the fossil form evidently comes under the genus Leiocidaris, Desor.
