412 
TIIK GROLOOIST, 
taohed and scattered masses of rock as tlicy should the boulder-masses in the 
drift. — Yours, &c., Great Yaiuioutii. 
Fossils from Girvan, Ayrshire. — Sir, — I shall be obliged if you can give 
me any information al)out the deposits in the immediate neighbourhood of Gir- 
van, Ayrshire. Some fossUs from a limestone-quarry there were sent me by a 
friend. They appear to be a species of Euomplialus ; but from the manner in 
which tlicy have been extracted from tlic quarry, only one side can be examined, 
the other oeing embedded in the limestone. 1 should be much obliged if you 
coidd inform me whether the limestone-deposits of GiiTan belong to the moun- 
tain-limestone or to the Silnrian period. — Yours, &c., W. M. B. A. — In 1850 
Sir Roderick Murehison and Professor James Nicol devoted some time to the 
examination of the Gu'vau neighbourhood, and tiie result was a memoir, 
illustrated by a nrap, sections, and plates of fossils, in the Geological Society's 
Journal (No. 27, vol. vii.) From this memoir we learn that the limestones at 
Craighead, Assel Burn, Aldeans, Graigneil, and Bogang are of Lower Silurian 
age ; and that the Hmestoncs south-east of Mullock HLU, and at Lemmy-lane 
are Carboniferous. 
The Euomphalus-looking fossd may possibly be a Maclurea, which is 
characteristically a Lower Silurian fossil, and is found near Girvan. 
Artificial Nodules : Venus'-Hair Stone. — Sir, — I trust you will ex- 
cuse my again troubling with a few small specimens, which I shall be ex- 
tremely obliged if you wiU name. 
The shells were taken out of a kind of smooth, round nodule, composed of a 
soft, sandy material of which I enclose a portion. It was brought to me lately, 
having been purchased at Dover ; its appearance was extremely artificial, being 
perfectly covered with small ammonites, shells, etc., embedded on the smface of 
this sandy nodule. 
The small brooch of what is commonly called Venus'-hair I enclose, because 
I am anxious to know its composition. I have another larger specimen of 
whicti the coloured streaks, rumiing transversely through one side of the 
crystal, are of a darkish brown colour, the crystal itself being perfectly clear, 
like the purest glass. — Yours &c., W. M. B. A., Mid-Lothian. — The nodules 
referred to are artificially made by mixing the dark green sand of the Upper 
Grcensand of Eastwear Bay, near Folkestone, with gum or glue. Immersion 
in hot water wiU at once detect this fraud, for which one or two persons at 
Dover are notorious. The fossils stuck on the outside are the commonest 
Gault fossils obtained from Copt Point and Eastwear Bay, such as Ammonites 
Imdus, A. splendem, A. fiibcrculatim, A. varicosus, Hamitss attenuatiis, Nucida 
pectinata, N. ovata, Inoceramus sulcaius, I. concent ricus, Dentalhm decussatum, 
D. eJliptirum, &C. 
Tiie fine long threads in brooch-stones, known as " Venus'-hair" are usually 
fibres of Asljestos or long acicular crystals of Titanium embedded in pure 
crystalline quartz. The " Venus'-hair" sometimes also consists of Actinolite 
or' Tremolitc, but that in the brooch-stone forwarded to us we believe to be 
Rutile (Titanium). Professor Tennant has in his collection a magnificent mass 
of pure quartz containing wire-like crystals of Titanium more than two inches 
Tertiary Strata West of Woolwich, at Pec:kham, &c. — After read- 
ing in the July number of The Geologist the description of that interestmg 
section of the Tertiary strata exposed at Woolwicli, many doubtless like myself 
visited that locality and returned gratified. On thinking that it might be pos- 
sible to trace that series inland or westwards, I concluded to try, and what little 
success I have met with may perhaps not be uninteresting to some of your 
readers. After leaving Woolwich in that direction, the first traces of the shell- 
bed which I found were in the cuttings of the Londim, Brigliton, and South- 
