Reports <k Proceedings — Mineralogical Society. 143 



III. MlNEKA LOGICAL SOCIETY. 



January 14. — "W. Barlow, F.P.S., Past-President, in the Chair. 



A. Hutchinson: "Stereoscopic Lantern Slides of Crystal Pictures."' 

 The twin pictures are projected by means of a double lantern 

 through screens of complementary tints — red and green — and are 

 viewed through similarly tinted screens, one for each eye. If the 

 adjustment is correct a black and white picture stands out in 

 relief. This method admits of the properties of crystals and of 

 crystal structure being demonstrated simultaneously to a large 

 number of students. — L.J. Spencer: "Mineralogical Characters of 

 Turite (= Turgite) and some other Iron -ores from Nova Scotia." 

 The mineral collection of the late Dr. H. S. Poole, which was 

 presented to the British Museum in 1917, contains, amongst the 

 iron -ores, specimens of magnetite, haematite, turite, goethite, 

 limonite, chalybite, mesitite, and ankerite, from many well-defined 

 localities in Nova Scotia. The dehydration curves and optical 

 characters of turite (2 Fe 2 3 . H 2 0), goethite (Fe 2 O s . H 2 0), and 

 limonite (2 Fe 2 O3 . 3 H 2 0) prove that these, at least, amongst the- 

 large group of ferric hydroxide minerals are distinct species with 

 crystalline structure; some others are colloidal. Turite (= turgite, 

 an incorrect German transliteration from the Russian) is a hard,, 

 lustrous, black mineral, with a radially fibrous and concentric 

 shelly structure, and gives a dark cherry-red streak ; the fibres are 

 optically birefringent and strongly pleochroic. Sharp brilliant 

 crvstals with the forms of goethite, but consisting of anhydrous 

 ferric oxide, i.e. pseudomorphs of haematite after goethite, were 

 described. 



COERESPOITDBlSrCE. 



YUNNAN CYSTIDEA. 



Sie, — In bringing (quite courteously) a general charge of inaccuracy 

 against my observations on the Yunnan Cystids, Dr. Cowper Reed 

 (Geol. Mag., February, 1919, p. 93) has confined his instances to- 

 two. (1) As regards the diplopores of Sinocystis loczyt, many of 

 which certainly appear at first sight to be covered with tubercles of 

 epistereom, I was able to detect the minute openings, just below the 

 apex of the tubercle, even in unworn surfaces from which I myself 

 cleared away the matrix (Geol. Mag., Nov. 1918, p. 512, fig. 5); 

 Dr. Peed was not able to see the openings in such unabraded 

 tubercles. Therefore, while maintaining that the pores normally 

 opened, I have admitted that they might occasionally become 

 clogged. (2) I am glad, to assure Dr. Peed that I have never 

 questioned the existence of the "runnels" on the surface of 

 Ovoeystis mansuyi. I have only denied that they are food-grooves. 

 Those on which I made notes from the actual specimen were 

 attributed to a combination of causes (Geol. Mag., 1918, p. 514). 



"When novelties are independently described by more than one 

 student, contradictory conclusions and divergent observations are 

 not uncommon. The matter is then generally decided by a fresh. 



