88 
NOTES AND MEMORANDA. 
about the T g- of a line in diameter. When detached from its position 
and placed in water, in a few minutes it projects in all directions a 
most wonderful and intricate net. Along the threads of this net float 
minute Naviculse from the neighbourhood, like boats in the current 
of a stream, until reaching the central mass they are there swallowed. 
Particles of dirt are also collected from all directions and are accumu- 
lated around the animal, and when the accumulation is sufficient to 
protect it, the web is withdrawn, and nothing apparently will again 
induce the animal to produce it. 
From these observations we may suppose that the Gromia terri- 
cola, as I propose to name the species, during dry weather remains 
quiescent and concealed among accumulated dirt in the crevices of our 
pavements, but that in rains or wet weather the little creature puts 
forth its living net, which becomes so many avenues along which food 
is conveyed to the body. As the neighbourhood becomes dry, the net 
is withdrawn to await another rain. The animal with its extended net 
can cover an area of nearly half a line in diameter. The threads of 
the net are less than the Trw<Xuoth of an inch in diameter. 
NOTES AND MEMOEANDA. 
A New Local Microscopical Society. — We learn from the energetic 
Honorary Secretary, Mr. John Hopkinson, jun., that a Natural History 
Society, which is intended to embrace also microscopical research, has 
just been established at Watford. We wish it every success, and we hope 
ere long to have to report its proceedings in these pages. The evening 
meetings of the Society will be held (by permission) in the rooms of 
the Watford Public Library, and during the summer months field 
meetings will also be held. It is proposed that the annual subscrip- 
tion be ten shillings, without entrance fee. The names of ladies and 
gentlemen willing to join the Society will be received by Dr. Brett, 
Watford House ; by Mr. Arthur Cottam, St. John’s Boad, Watford ; 
and by Mr. John Hopkinson, jun., Holly Bank, Watford. 
The Illumination of Difficult Test-objects— The Use of Blue Glass. 
— Mr. J. E. Smith [U.S.A.] has recently described a method which strikes 
us as not particularly novel in principle, though it has some originality 
of detail. The following is the author’s own account of the mode. My 
present method of using a single plate of blue glass will recommend 
itself by its perfect simplicity ; in fact it is hardly any more trouble 
than the use of ordinary diffused daylight. My method is as follows : 
Select any ordinary small table, say 2 feet square, with square sides. 
Provide also a pane of blue glass. This pane of glass should be about 
12 x 18 inches, although a smaller size would answer. Next provide 
a cleat of ^-incli wood, about 12 inches long by 3 or 4 inches wide. 
Fasten this cleat, with two screws, to one end of the table, the top of 
cleat being flush with surface of table, leaving, however, space enough 
between the table and the cleat to insert the edge of the 12 x 18 pane, 
