30 



KNOWLEDGE. 



January. 1911. 



had only just attained maturity. I am unable to report on the 

 contents of these small nests early in the summer as they were 

 not then in existence. Large nests, however, examined in 

 May, contained, on the testimony of local collectors, a 

 comparatively large number of females, the males being stated 

 to be very rare in the adult state. 



Dr. Randell Jackson, who has kindly forwarded me a 

 northern specimen of this species, also reports a great 

 preponderance of females amongst his captures. A detailed 

 description of the spider would be out of place here, but the 

 following characters will suffice to distinguish it from its 

 allies : — Eyes small and very widely separated ; front row- 

 straight by their bases in female, by their centres in male. 

 Posterior eyes strongly procurved (in the male this row of eyes 

 is distorted by the exaggeration of the caput). Legs fairly 

 long. Femora, each with two rows of bristles on the under- 

 side. Tibial spine very small, close to base of joint. 

 Metatarsi I. II and III with sensory bristle; in III it is 

 just beyond the middle; in I it is about two-thirds from the 

 base. Tarsi not much shorter than metatarsi ; somewhat 

 fusiform, especially in the male. 



The species most likely to be confounded with 

 Tliyrcosthciiiiis biovatiis is Pepuiiocraniuni ludicrum, 

 which agrees with it pretty closely in size and general 

 appearance, and which possesses, in the male sex, a some- 

 what similar cephalic protuberance. It occurs also in pine 

 and heath districts, and is not uncommon in many parts of 

 the South of England. The specimen purporting to be a male 

 Tliyrcvsthcniiis. presented to the British Museum by Mr. 

 Donisthorpe, is, in reality, nothing but Pepoiiocraninin 



'"'!''''■"'"■ F. P. Smith. 



QUEKETT MICROSCOPICAL CLUB.— November 22nd, 

 mfo, Mr. E. J. Spitta, L.R.C.P., Vice-President, in the chair. 

 A paper on "A Water Mite new to Britain {Xeiituania 

 triangularis, Piersig)" contributed by Mr. Geo. Plant Deeley. 

 This genus was formerly called Cochleophorus. and several 

 species are described under this generic name by Mr. C. D. 

 Soar, in Science Gossip. June, 1900. The locality from 

 which Mr. Deeley obtained his specimens was Parkhill. 

 Stourbridge. Both sexes were taken. — Mr. T. B. Rosseter, 

 F.R.M.S.. on "'A new species of .Avian Tape-worm 

 {Hynienolepis npsilon)." He found it in January, 1910. 

 parasitic, amongst the faeces of the intestine of a Wild Duck 

 {Anas boschas). The author gave an account of its 

 affinities, references being made to the work of Schilling 

 (1823), Creplin (1829), Dajardin, Pagenstecher I1S5S). Pfaff 

 and Olrix, and Krabbe (1867). A full description of the 

 specific characters of the new species was given, and from the 

 similarity of the uterine sac to the Greek small i\ the name 

 upsilon was bestowed on it. — Mr. James Burton on Botrydinni 

 grannlatuni. "The plant consists of small green balloon- 

 shaped vesicles about three millimetres in diameter. Below 

 the surface of the mud an extensive root system is produced ; 

 the roots branch dichotomously and extend to a considerable 

 distance, often reaching a length of six millimetres. As the 

 plants very often grow thickly side by side, the roots are 

 entangled and interlaced in the mud, and, the whole 

 plant being of somewhat tender consistency, it is difficult 

 to extricate perfect specimens. The upper part, when 

 young, is filled with protoplasm and is bright green in 

 colour. Later the centre becomes more watery and 

 the green is seen to be due to finely granular chlorophyll. 

 The colourless roots are filled w'ith watery protoplasm. .As to 

 its classification. Professor West classes it with the group 

 Heferokontae. All the older books put it among theSiphoneae, 

 and it seems, for several reasons, to be very appropriately 

 placed there. One of the interesting facts connected with 

 Botrydinni is that, although it is of such considerable size, it 

 is unicellular. In thinking of a unicellular organism — plant 

 or animal — we usually consider it as something very small, 

 or even microscopic, in size ; but that is not necessarily the 

 case. The Siphoneae are a class grouped together because 

 of the noticeable characteristic that they are all unicellular, 

 notwithstanding whicli. most of them are of considerable size. 



The best-known member of the group is the exceedingly 

 common Vanclieria. There are many species — some terrestrial, 

 and found on the damp earth of flower-pots and on damp 

 garden-paths: others occur in ponds. In these plants, though 

 they reach a length of several inches, and sometimes nearly a 

 foot, no dividing-walls appear in the filaments under normal 

 xegetative conditions. Most of the family are marine and 

 one genus — Cff;(/t'r/>(T, occurring in the Mediterranean — reaches 

 a length of several metres, and yet is only one cell. 



Mr. Herbert F. Angus, of the firm nf H. F". .Angus & Co.. 

 exhibited and described a number of Microscopes by 

 R. Winkel. of Gottingen. who, he said, enjoyed a high 

 reputation in Germany, although almost unknown in England. 

 He pointed out that the model was of the more or less 

 stereotyped Continental pattern, inclining more to the Zeiss 

 model than any other, but diftering in several important 

 details, as was only to be expected in the productions of an 

 old-established firm who had given proof of their originality in 

 the past by first employing fluorite in the construction of 

 objectives, and producing an objective with a hyper- 

 hemispherical front lens. 



A ROCK GRINDING MACHINE FOR AMATEURS.— 

 Nearly everj' amateur microscopist who has taken up the 

 study of petrology has at some time felt desirous of preparing 

 thin sections of rocks for himself instead of purchasing them, 

 but has in a good many cases been deterred by the labour 

 involved in grinding them by hand. This method will answer 

 the purpose if only a few slides are required, but when he 

 takes up the matter seriously and wishes to make large num- 

 bers of sections the student finds the necessity of having some 

 mechanical means to minimize the work. 



The professional lapidaries' lathes, and also the special rock 

 slicing and grinding machines placed on the market for 

 petrologists, are generally speaking far more expensive than 

 the average amateur can afford, and I therefore wish to 

 describe a home-made apparatus which has been found to 

 give good results, and to be fully capable of doing the work 

 for which it was devised. 



Figure 2 gives a general view of the entire machine, and 

 Figure 1 shows the top of the table and the way in which the 

 various parts are disposed. 



The cost of this machine complete is. roughly speaking. 

 17s., and it can be made by anybody capable of using 

 ordinary tools. 



Tlie apparatus is erected on an ordinary sewing machine 

 table, which can be procured very easily. For the slitting 

 disc, which is shown on the right hand side of Figures 1 and 2, 

 it is necessary to get an ordinary polisher's lathe head. This 

 is threaded at one end to take a circular saw or emery wheel, 

 and upon this thread is run the cutting disc, which is then 

 bolted on in the same way as a circular saw. I use a plain 

 disc of soft iron six inches in diameter, and about one-fiftieth 

 of an inch thick. 



The rock-holder is the most elaborate part of the arrange- 

 ment, but is quite simple to manufacture. Figure 3 is a 

 near view of this on a larger scale. It consists of a 

 spindle six inches long, an upright to carry the same, and the 

 jaws to hold the rock. Four and a half inches of this spindle are 

 three-eighths of an inch in diameter threaded sixteen to the 

 inch, and the remaining one and a half inches are a quarter of 

 an inch in diameter, and threaded to take the cones of an 

 ordinary bicycle pedal. This spindle was made for me by a 

 working cycle maker. It is carried on an upright cut out of 

 oak three-quarters of an inch thick. This has a threaded plate 

 screwed on each side of it. through which the spindle moves. 

 There is a lock nut on the spindle behind the upright to hold 

 it rigid. To the end of the spindle are attached the jaws for 

 holding the rock. This portion consists of a piece of oak 

 three quarters of an inch thick, three and a half inches long by 

 three inches wide. To the bottom of this is screwed a piece 

 of oak a quarter of an inch thick, and on top of this is a 

 moveable piece which is clamped on the rock by the butterfly 

 nuts of the two three-inch bolts. 



The upright portion of the jaws is fastened to the spindle 

 by the ball bearings of an old bicycle pedal. When the 



