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present placed in that genus, -with the trivial name of A. ? Selwyni, in 
honour of Dr. A. E,. C. Selwyn, D.E.S., Director of the Geological and 
Natural History Survey of Canada, and formerly Director of the Geological 
Survey of Victoria, Australia. The teeth are large, quite two-thirds of an 
inch in length, and very strong. 
Localiiij and Horizon . — Nowra, Shoalhaven Diver, Co. St. Vincent: — 
Nowra Grit (equivalent of the Muree Dock of the Hunter Diver Coal-field) — 
Upper Marine Series. 
Arcu^eocidaris, s]i. ind. 
PL xxir. Pig. 1. 
0^5.— In all probability a second species of Arclueocidaris exists in 
our Permo-Carboniferous rocks, as exemplified by the fragmentary specimen 
represented in PI. XXII, fig. 1, for which we are indebted to Mr. John 
Waterhouse, M.A., Inspector of Schools, Dungog. The specimen consists 
of portions of eight rows of interamhulacral plates, four close together, 
practically in apposition, separated from two of the others by the faint 
impression of an ambulacrum. The remaining jiortions of rows are at the 
opposite extremity. The more or less radiating manner in which these rows 
are disposed leads me to believe that the central unoccupied sjiace of a lighter 
coloured matrix may represent one or other of the poles. 
I believe this to be a species distinct from A. Sehoyni on account of 
the more transverse shape of the plates, the almost square-hexagonal outline 
of those of the latter species being one of its chief characters. The primary 
tubercles of the present species are particularly well marked. One of the 
ambulacra is just indicated by the impressions of a few plates, but too 
imperfectly for description. 
Locality and Horizon . — Quarry near road passing Dagworth, about five 
miles south of West Maitland, Co. Northumberland {J. TFaterhoiise, 
H.A.) : — Upper Marine Series. 
