21 
the pigmentary matter, which imparted the colour to the shell, was to 
be found. 
The meeting then became a Conversazione, when 
Mr. Hewwan exhibited under Gundlach’s 1-12th and 1-16th, 
sections of crab and cowrie shell, mounted with thick covers. The 
performance of the 1-16th was perfect. Afterwards, for lined objects 
Pleurosigma Angulatum and tasselled scales of white butterfly were 
shown. The 1-16th gave very good results ; but the 1-12th did not 
equal a Beck’s Popular 4th, 
Mr. Szwett exhibited, under a }, out of the first parcel and 
pronounced by Mr. Henna# a perfect lens, sections of pearl and crab 
shell. This lens was pronounced very good. 
Mr. Pero, under a 3 and an inch with convex front, exhibited 
sections of pinna shell. Both these lenses were excellent. 
Mr. Wonror, undera couple of 1-3rds, exhibited egg-shell of garden 
snail, sections of terebratula, shells of prawn, shrimp, &e. These 
lenses were very good, and, when compared with Mr SEWELL’s 4 to 
test quality of performance, were so much alike that scarcely a 
difference could be detected. 
Mr. R. Guarsyer exhibited shells of nautilus, &c., cut through to 
show their chambered character. 
January 12rx, 1871. 
ORDINARY MEETING.—MR. J. HOWELL ON “THE 
BRIGHTON CLIFF FORMATION AND THE 
BRIGHTON VALLEY.” 
A section of the Brighton Cliff Formation is 1. Soil ; 2. Weather- 
worn flints; 3. Chalk-rubble, locally termed coombe-rock ; 4. Old 
sea beach; 5. Sand; 6. Chalk with veins of flints. This was des- 
cribed as the peculiar deposit upon which a large portion of Brighton 
stands, being essentially Post-Pliocene, and, probably, formed about 
the close of the Glacial epoch. In the west of Brighton the chalk is 
