30 
THE GEOLOGIST. 
particular conglomerates I am describing would, however, appear to pre- 
sent somewhat different conditions, the barren portions being at the bot- 
tom and the shelly masses forming the upper stratum, — suggestive, per- 
haps, that the shells, being light and comparatively large, took a superior 
position, whilst the more weighty sand was washed or shaken through, ou 
the principle that causes the larger and unbroken biscuits, if I may be al- 
lowed the simile, to occ-apy the upper part of a cask, while the dust and 
"midshipmen's nuts " just as assuredly seek the bottom. 
In consequence of the foldings and contortions to which these Silurian 
beds have ])een subjected, as may be supposed, a great A^ariety, both of 
fossils and lithological characteristics, are crowded into a comparatively 
small space. I^ear the Botanical Gardens, situate on the southern banks 
of the Yarra-yarra, and not far removed from two of the Elvan dykes 
marked on the map, the strata are composed of soft micaceous sand- 
stone, generally friable, and apparently much broken up and dislocated by 
past convulsions. 
The fossils in this locality are numerous, but small in size ; Orthidaj, 
Leptsense, with a kind of spiral univalve, probably a Euomphalus, being 
the prevailing types. Close beside the beds wlierein these organisms pre- 
vail are others destitute of fossils, but containing nearly spherical bodies 
of perhaps half an inch in diameter, and genei'ally having a badly defined 
stem-like projection on one side, the stem being sometimes continued for 
several inches, until ultimately lost in the surrounding matrix. On being 
newly fractured, these bodies appear of a fine lake colour, mottled with 
lighter tints, but fade and become dim after a few days' exposure to light 
and air. They are not yet named in the University Museum, although 
some few are therein exhibited. An infiltration of peroxide of iron and 
manganese may perhaps account for both the colour and the phenomenon ; 
but it is questionable whether these latter substances may not have been 
attracted by some animal or vegetcible remains for:ning a nucleus, which 
has since disappeared. 
In a quantity of stones recentl}^ excavated from a sewer communicating 
with the Parliament Houses and Treasury — a manor particularly poached 
over by myself — I have met with Holopellse (F), Orthidae (very small), 
Cuculellaj (the shells still attached to each other, but generally open and 
filled with the surrounding stone), broken fragments of an Orthoceratite 
with transverse corrugations, Trilobites, and Creseis Furhesii. These 
latter pteropods, I believe similar to a species now found in the Mediter- 
ranean, are especially numerous. The general size is 1| to 2 inches, al- 
though one specimen, unfortunately fractured, must have been nearly 5^ 
inches in longitudinal dimensions. 
The above are nearly always found in the soft sandstones of the locality, 
whilst the shales of the same place contain large quantities of a species of 
worm many inches in length, which I do not find depicted in any work on 
the Silurian deposits in my possession. 
At Carlton Butts, about 1^ mile north-east of Melbourne, the fossils, 
although thinly scattered, are remarkable for being in a remarkably fine 
state of preservation. Shales and sandstones predominate in this locality 
also, but are much harder than in the place last described. A peculiarity 
of the fossils found in this spot is their singularly rich colouring when 
only recently obtained. On laying open, at a single blow of the hammer, 
a fine specimen of the tail portion of an Asaphus (P), as it appeared a 
beautifully sculptured and lake-tinted object on the cream-coloured mass oi 
surrounding stone, I almost thought the fossil some new species of moth oi 
butterfly miraculously imprisoned in a rocky matrix. The colouring is nol 
