238 James Small 
cellulas minutissimis triangularibus; lamella externa membranae 
saepe in forma mitrae circularis vel quadrangularis soluta est; chro- 
matophora singula (?) in quaque cellula cum pyrenoide; multiplicitis 
non satis cognita. 
Diam. coenob., ca. 35 /x; diam. cell., 10-14 jit,. 
My thanks are due to Prof. F. E. Fritsch for the generous help he 
has given me in studying this little organism. 
Granville School, 
Leicester. 
NOTES ON AN EASY METHOD OF CAMERA 
LUCIDA DRAWING 
By JAMES SMALL 
(With 2 figures in the text) 
A combination of Baker’s “Reflex Drawing Apparatus” with an 
Ediswan “Pointolite Lamp” has proved so satisfactory in 
working that these notes have been written to make known the ease 
and speed with which a clear camera lucida drawing can be made by 
this method. 
The Reflex Drawing Apparatus 1 is a small right-angled prism 
with the 45 0 side silvered (the whole protected by metal fittings), 
which is affixed by means of a small screw upon the top of any 
ordinary eyepiece. It possesses several advantages over the larger 
mirrors in common use. Firstly, it is small, convenient to handle, 
easily adjusted, and when affixed to the eyepiece it can be readily 
turned up so that the field may be viewed through the mirror from 
above. Secondly, the mirror surface is protected by glass which is 
exposed only to a small extent; this largely obviates the numerous 
cleanings necessary with the larger mirrors, and the deterioration of 
the surface which is a consequence. Thirdly, since the rays pass into 
1 Sold by C. Baker, 244, High Holborn, London. Price, 17s. 6 d. 
