70 
The slide of rock-specimen No. 65, exhibits very strikingly “ shear ” 
or schistose structure. A microscopic examination shows this limestone to 
contain numerous crinoid remains and carapaces of ostraeoda, with an 
occasional pellet formed by the minute tubular organism, Girvanella. The 
crinoidal plates and ossicles form eyes, or lenticles, around which stream 
the finer, granular, calcitic particles (see PI. I., fig. 2). A particularly 
interesting feature of this limestone is the inclusion of numerous flakes of 
biotite (black mica) and pale green chlorite, interlaminated with the calcite 
constituents; whilst here and there may be seen some contorted bands 
of tuffaceous fragments. This clearly suggests the outburst of tuffaceous 
andesitic ejectamenta contemporaneously with the deposition of the lime¬ 
stone, as illustrated, for example, by the calcareous organic tuffs forming 
in the proximity of volcanic islands at the present day. 
Fossil Determinations. 
Specimen Number. 
Fossils, with remarks thereon. 
204 
Crinoid remains. 
205 
Crinoid remains. In thin section this rock is seen to 
contain Girvanella , (?) Alveolites , and a stromato- 
poroid, with structure obscured by crushing and 
recrystallization. 
206 
Crinoid remains. 
207 
Fistulipora sp. (PI. II., fig. 3). See description at 
end of report. 
Crinoid plates and ossicles, numerous. 
Ostraeoda, probably a species of Primitia. 
This rock is more or less “ sheared,” and shows some 
biotite between the ‘folia. 
208 
Crinoid remains abundant (PI. I., fig. 1). 
209, 210 
Crinoid remains. 
65 
Girvanella (PI. I., fig. 2). See description at end of 
report. 
Crinoid remains. 
Ostraeoda, apparently referable to Primitia (PI. I., 
fig. 2). 
Specimens from Tyers River, (no. 41 on locality map.) 
These are numbered from 58 to 64 (including 64A), 66 to 77 (including 
77A), and 211 to 213. 
Lithological Characters. —Nos. 58 to 63, 64A, and 211 to 213, are 
dark, umber-coloured mudstones, practically devoid of calcareous matter, 
with occasional traces of fossils (casts). These rocks are more or less 
regularly bedded, and, in certain cases, tend to become conglomeratic. 
The general structure points to their having been 'formed under shallow 
water conditions. 
Nos. 64, 66 to 77, and 77A are fossiliferous limestones, varying from 
brownish-grey to Bark-grey, and weathering to a bright brick-red colour. 
They are rich in crinoid and coral remains, and the particular bed from 
which they were taken promises eventually to prove a veritable storehouse 
of Silurian fossils. 
