Nullipores & Sponges of the Boulder Clay of Caithness, 99 
Burn on one of my official visits, I noticed the sections of 
boulder clay exposed there ; not having time then to devote 
to their examination, I thought that, although fourteen miles 
distant from Wick, I would try my pedestrian powers and do 
so, on the day kept for the Queen's birthday (1855), should 
the weather prove fine. It did, and I was off early in the 
morning, so that I might have a long search, not only in the 
exposed sections of the boulder clay on my route, but every 
cjuarry and place of interest. On searching the Burn of Fres- 
wick, I commenced immediately at the bridge, and in the blue 
clay there found several flints, evidently from the chalk, 
hinges and portions of Cyprina, fragments of Turritella, Den- 
talia, &c., all more or less broken and rubbed. These were 
firmly embedded, and so were all the specimens taken by me 
from the boulder clay. After examining the sections above 
the bridge, I retraced my steps, passed over the road and down 
the burn towards the castle, and in a nice section worn by the 
stream, as well as the usual stones, shells, &c., I met with a 
white mass, which at first, from its yielding freely to the 
knife, I thought chalk. After digging it out and washing it 
in the stream, I was surprised to find that it would swim like 
cork, and therefore could not be chalk. I put it carefully 
into one of my boxes, and searched again, and at some distance 
from the spot where I found the first I got a smaller piece of the 
same description. They are the only pieces I have met with. 
I have forwarded the smallest piece with this paper, enclosed 
in glass, and hope that you will excuse my jealous care in 
thus preserving the precious relic. As soon as I had fully 
examined all the exposed clay, I turned my steps homeward, 
wondering all the way what my swimming prize could be. As 
soon as possible, after washing and taking my tea, I out with 
a microscope, and placed a small portion of the mass under it, 
when, to my delight, bundles of spiculse, and quantities of 
siliceous globules, were beautifully shown, as well as straight 
spicula, triradiate, and other shapes ; the spicula hollow in the 
centre. I fancied it might be a Fachymatisma ; but then 
the stellate forms were absent. It effervesced freely in dilute 
muriatic acid. In order to be set right, I forwarded a portion 
of each piece to Mr Bowerbank of London, who, with his usual 
