252 PROCEEDINGS OF THE 



inferior. But this new loup exhibits none of these defects, and 

 Koristka is to be congratulated on having brought out at a low- 

 figure a loup which compares favourably in the quality of its 

 finish with the most expensive grades of work in this line. This 

 high standard of workmanship extends also to Koristka's 

 objectives, eye-pieces and other apparatus. 



Mr. A. A. C. Eliot Merlin, F.R.M.S., sent a note on " Secondary 



Hairs on Foot of a Ceylon Spider." The main hairs on the foot 



of a very large species of Ceylon spider, the name of which is 



unknown, have proved to be densely covered with small short 



spines or hairs so transparent as to be observable with difficulty 



even by means of an oil-immersion objective. The specimen 



examined was obtained and mounted in balsam by the late 



Staniforth Green, who was for many years resident at Colombo. 



When the main hairs are viewed with a dry lens, of moderately 



large aperture they plainly exhibit a regular clotted structure, 



this being composed of the ring root sockets of the secondary 



spines, which are themselves so transparent in the balsam mount 



as to require great aperture to define properly. It is suggested, 



however, that hairs from this, or similar, large species of spider 



might be mounted in glycerine jelly and might then exhibit the 



spines more easily. The preparation in which the spines have 



been noted happens to be, like most entomological mounts 



intended for examination under low or medium powers, provided 



with a cover-glass of considerable thickness, while the foot itself 



is large and by no means flat. Under these conditions an 



ordinary oil-immersion objective could not be employed, but 



fortunately a Powell one-twelfth achromatic, of measured N.A. 



1*27, obtained some fifteen years ago, possesses quite abnormal 



working distance compared with recent productions of similar, or 



slightly greater, aperture, and is to oil-immersion lenses what 



the new one-sixth moderate aperture objectives of great working 



distance are to dry systems. The lens in question has on several 



occasions proved invaluable for the examination of minute 



structure in ordinarily mounted entomological specimens. A 



photomicrograph at x 60 accompanied the paper for identification 



purpose, and was exhibited. 



Mr. Nelson sent for exhibition a section of Green Trap, basic 

 igneous rock, a crystalline aggregation of serpentine. This, he 

 wrote, might easily be mistaken for a piece of fossil nummulite, or 



