26 J. W. Gregory—A new Protaster from Australia. 
alternate in the arms, but in the disk, which includes the first 
three pairs, they are merely subalternate. The ambulacral ossicles 
are much thicker than those of other species of Protaster, and they 
are consequently less numerous. They are separated by double 
concave spaces, which served for the passage of the tube feet (or 
of the ampulle, if, as is not improbable, the tube feet were arranged 
on the Asteroid type). The adambulacral plates are long and quad- 
rangular, running parallel to the arms, each slightly longer than the 
corresponding ambulacral ossicle. 
The actinal aspect of the arms is not well exposed in any of the 
Specimens; in one, however, the end faces of the adambulacral 
plates are seen, as at their aboral extremities they curve actinally. 
Neither the articular facets of the ambulacral ossicles nor the 
arm spines are shown. 
Locality and stratigraphical position—The specimens were found 
in the so-called ‘‘Mayhill Sandstone” of Moonee Ponds, Flemington, 
near Melbourne; they are Upper Silurian in age, but there seems 
no sufficient reason for regarding the beds from which they have 
been derived as in any way the equivalent of our Mayhill Sandstone. 
The rock is a yellowish, fine-grained, micaceous sandstone, from 
which all calcareous matter has been dissolved, so that the fossils 
occur only as casts and impressions coloured by iron oxide. 
Affinities of the species.—The only species of Protaster for which 
this could be mistaken is P. leptosoma, Salter, trom the Leintwardine 
Flags of Ludlow ; from this, however, it may be readily distinguished 
by the shape of the mouth-frames and of the ambulacral ossicles. 
In a list of fossils from the Upper Silurian rocks of Victoria, 
published by F. M‘Coy in 1874,' the MS. name of Teeniaster australis 
is recorded from the Upper Yarra. This may refer to the species 
here described, which at first sight, in specimens that do not show 
the disk, is not unlike a Zeniaster ; in the absence of any description 
of M‘Coy’s species, it is quite impossible to say whether such is the 
case, and as the specimens do not come from the same locality, 
though some of the Asteroids recorded are from Moonee Ponds, it 
would not be safe to adopt M‘Coy’s manuscript name. It serves, 
however, to remind us of the differences of opinion as to the 
relations of Teniaster and Protaster, which Hall? maintained were 
very closely allied, if not identical, attributing the supposed differ- 
ences between them to errors in description by Salter.® According 
to the original description by Billings,‘ Toeniaster differed from 
Protaster in the absence of a disk, in the development of the oral 
plates from the adambulacral plates and not from the ambulacral 
elements, and in that the pores pass through the spaces between the 
' R. B. Smyth, Progress Reports, Geol. Survey, Victoria, No. 1, Melbourne, 
1874, p. 34. 
2 a) Hal 20th Regents Report, Albany, 1867, pp. 298-4 and 300-1. 
3 J. W. Salter, On some new Paleozoic Starfishes, Ann. and Mag. Nat. Hist. ser. 
2, vol. xx. 1857, pp. 330-2, pl. ix. figs.4 and 5; and Additiunal Notes on some new 
Palzozoic Starfishes, ser. 8, vol. viii. 1861, pp. 484-6, pl. xviii. figs. 9, 10, and 11. 
4 Ii. Billings, On the Asteriade of the Lower Silurian Rocks of Canada, Canadian 
Org. Remains, dec. iii, Montreal, 1858, p. 80-1, pl. x. figs. 8 and 4. 
