PROCEEDINGS OF THE SOCIETY. 571 



He quite agreed with Mr. Beck that it was not worth making, because 

 eve-pieces were now so extraordinarily cheap. 



A New Microscopical Lamp, designed by Professor Emrys-Roberts, 

 was exhibited by the Secretary, who read the following description pre- 

 pared by Professor Emrys-Roberts : — This lamp has been designed to 

 combine simplicity with efficiency. Incidentally, by using standard 

 fittings, the cost of production has been reduced to a minimum. The 

 base is brass, heavily weighted, and covered beneath with baize to pre- 

 vent damage to desk or bench. The upright is brass tubing bent to a 

 convenient curve so as to accommodate the light. At the angle is a 

 universal joint, which can be tightened so as to fix the light in any re- 

 quired position. The parabolic shade or reflector is made of plated metal. 

 The Osram light is frosted below, and so no points of light from the 

 filaments are visible. For general microscopical work it has been found 

 to be both useful and convenient. 



Mr. Scales said that the author enclosed an extract from the British 

 Medical Journal of April 15, in which he described it. As far as he 

 (Mr. Scales) could see, it was an ordinary Osram lamp with parabolic 

 reflector. It was compact, and could be switched on to any circuit. 

 There, in his opinion, its virtues ended. Ordinary frosted lamps were 

 in common use in laboratories, but they were unsuitable for decent 

 work ; and when he saw this lamp mentioned in the British Medical 

 Journal he felt sorry that it had been put forward as the type of lamp 

 suitable for work of good quality in an ordinary laboratory. The lamp 

 is manufactured by The General Electric Company, Limited. 



In regard to the diatom slides which Mr. Allan had sent, that 

 gentleman said he would be very grateful if any members or Fellows 

 would name some of the specimens. 



Referring to the two slides of Aulacodiscus superbus presented by 

 Mr. Norman Thomas in October 1909, and April 1911, 



Mr. Spitta said it was well-known that the Aulacodiscus was a genus 

 of great beauty ; he said this with all diffidence, as he was not a certified 

 diatomaniac, but still he was very fond of the subject. The peculiarity 

 about the Aulacodiscus was, that a large number of the varieties were 

 so difficult to obtain. Van Heurck mentioned but a few. He believed 

 that the only treatise extant on the subject was one by Mr. Rattray, in 

 the Proceedings of the Society for 1888 — the October Proceedings, 

 published in December. He thought that in this work 127 varieties 

 were given ; but on looking through the catalogues of those who sold 

 diatoms it would be found that rarely were there more than a dozen men- 

 tioned, though in one or two instances as many as fifty might be given. 

 The remaining ones were very rare. Very few specimens of A. superbus 

 had been seen since it was originally described by Kitton in 1857. His 

 description did not exactly correspond with the specimens that Mr. 

 Norman Thomas had sent. Many opinions had been advanced as to 

 what was the cause of the rarity of these forms, and one was that those 

 varieties needed a certain environment, and that otherwise they would 

 not grow. A certain element of probability was lent to that view by 



