198 



NATURE 



[May 9, 191: 



the period with slender Capricorn whorls by accelera- 

 ting the development of bituberculation and prolonging 

 the period of pre-costate globose whorls. The fol- 

 lowing genera may be recognised ; each includes Am- 

 monites of the three types mentioned above : — (i) An 

 earlier group, with tubercles paired in the involute 

 stages; Radstock (Somerset) is the onlv British locality 

 where these Ammonites have been found. (2) A later 

 ^roup, with unpaired tubercles in the involute stage. 

 These genera are most readily distinguished by sutural 

 characters, namely, the relative depths of the' external 

 lobe (EL) and the first lateral lobe (IL), and bv the 

 width of the external saddle (ES). (a) With narrow 

 ES (not reaching to the outer tubercles), {h) With 

 wide ES, reaching to the outer tubercles. These Am- 

 monites generally occur in the upper part of the Lower 

 Lias, where it has been usual to recognise a capri- 

 cornus zone overlying a striatus zone. There are 

 several horizons with Capricorn Ammonites of different 

 series, and several with the involute forms evolved 

 from them. In no locality examined is the complete 

 sequence shown. The absence of some groups is due 

 to the original distribution of the Ammonites; in other 

 cases it is due to non-sequences. Two groups of Lias 

 Ammonites are recognised, namely : (i) those which 

 were evolved directly from a globose ancestor, and 

 (ii) those which passed through an intermediate broad- 

 ventered (cadicone) stage. 



Royal Microscopical Society, April 17.— Mr. J. E. 

 Barnard, (president, in the chair. — J. M. Brown: 

 Pyxidicula invisitata, a Rhizopod new ,to Britain, and 

 Hedriocystis spinifera, a new Helizoon. The first- 

 named appears to be widely distributed in Britain, 

 but has not apparently been referred to bv anv author 

 since first described ,by Averintzeff. The second species 

 is related to H. reticulata, Penard, but is smaller, has 

 no pedical, and is provided with spines at the angles 

 of the facets of the capsule. — E. Atkinson : Hypo- 

 ■eutectoid steel. Details' of a systematic research 

 <R.288) were given, the investigation /being conducted 

 to find the cause of failure in a hypo-eutectoid steel 

 of the middle carbon range. In turn each of the fol- 

 lowing was dealt with :— (i) Mechanical lest by labora- 

 tory adaptation of the Brinell test; (2) evolution of 

 H^S -for printing; (3) tensile testing; (4) chemical 

 composition ; (5) computation of pearlite, MnS, and 

 ferrite to be expected under the microscope; (6) ^ 

 complete series of photomicrographs showing enclo- 

 sures of MnS, peaflite, sorbitic pearlite, banded ferrite 

 or "ghost lines." .Structural deformation and tvpes of 

 micro-structures were rarely met with. Then followed 

 several illustrations of normal steels with varying per- 

 centages of carbon, commencing with an almost 

 pearlite-free iron. The paper also embraced the pre- 

 paration of specimens, development of structures by 

 "etching," and the lens system used in the author's 

 laboratory for illuminating the specimens. A brief, 

 though very thorough, description of the manufacture 

 of hypo-eutectoid steel concluded the paper. — E. ]. 

 Sheppard : Two valuable methods of staining in bulk 

 and counter-staining. The author described a new 

 method of stainine: in bulk with carmalum and 

 counter-staining with light green, and a second method 

 of staining in (bulk with iron hasmatoxylin and counter- 

 staining with erythrosine, both of which methods gave 

 excellent results. 



Linnean Society, April 18.— Sir David Prain, presi- 

 dent, in the chair. — Prof. J. P. Hill : An expedition 

 to Brazil in 1Q13. The expedition was supported by 

 grants from the Government Grant Committee and 

 ■Council of the Roval Societv, and the trustees of the 

 Percy Sladen Fund. The primary object was to obtain 

 NO. 2532, VOL. lOl] 



material for studying the development of certain 

 American marsupials, the most familiar being the 

 American opossum. When the expedition was 

 organised, our knowledge of the development of 

 Didelphys rested on the incomplete account given by 

 Emil Selenka in 1886; the author's own observations 

 on the Australian native cat, Dasyurus, differed 

 essentially from Selenka's statements, and it was 

 hoped to get the facts concerning them. Another point 

 was to determine the development of those genera 

 regarded on anatomical grounds as nearest the base of 

 the Didelphyd series, namely, Marmosa and Peramys ; 

 these are small rat-like creatures, remarkable for /the 

 entire absence of the pouch so characteristic of the 

 other members of the order. Summing up the results, 

 the expedition may be regarded as successful, though 

 all its objects were not attained. Besides the material 

 for anatomical investigation, a small collection of 

 rodents was brought back, about eight genera of 

 Muridae, and an interesting series of frogs, about 

 twenty-two species, two being new. 



Manchester. 



Literary and Philosophical Society, April 23. — Mr. W. 

 Thomson, president, in the .chair. — Dr. E. Newbery and 

 H. Lupton : Radio-activity and the coloration of 

 minerals. A number of mineral specimens were 

 examined as to their behaviour (a) on heating, (b) on 

 treatment with radium or cathode rays before or after 

 heating, and (c) on heating after treatment {b). 

 Several brilliant colour effects were obtained, among 

 which may be mentioned the complete restoration of 

 the original colour to green fluorite, smoky quartz, 

 zircon, topaz, etc., which had been decolorised by 

 heat, the production of a fine deep blue colour in a 

 colourless fluorite from Matlock by radium, an intense 

 purple in colourless fluorite from the Pyrenees by 

 cathode rays, and an indigo blue in transparent barytes 

 by radium. A bright green thermo-luminescence was 

 imparted to all the fluorites used, and their original 

 violet thermo-luminescence was also restored if that 

 had been destroyed by previous heating. A Spanish 

 phosphorite gave a brilliant yellow thermo-luminescence 

 which was restored with increased strength by radium 

 or cathode rays. It was concluded that many minerals 

 owe their colour and thermo-luminescence to the 

 presence of radio-active matter either in the water 

 from which they have been deposited or in the sur- 

 rounding rock. Traces of certain inorganic impurities 

 are acted upon by a, /?, or y rays and dissociated, the 

 size or density of the resulting particles determining 

 the colour produced. On heating, the dissociated atoms 

 recombine with evolution of light and loss of colour 

 to the mineral. 



Dublin. 



Royal Dublin Society, March 26.— Dr. G. H. Pethy- 

 bridge in the chair. — R. G. Allen : The electrical resist- 

 ance of porcelain at different temperatures. The results 

 of testing the insulation resistance of eight samples ot 

 various forms of porcelain were given for temperatures 

 ranging from about 20° C. to nearly 300° C, and these 

 results showed that for each the simple relation be- 

 tween insulation resistance and absolute temperature 

 previously given by Rasch and Hinrichsen was con- 

 firmed. A means of discovering the identity of a 

 sample of unknown porcelain was also pointed out. — 

 J Doyle : Observations on the morphology of Larix 

 hptolepis (two papers). The first part deals with the 

 d^velooment of the double pollen grains. Owing to the 

 obliquity of the first division spindle, even through a 

 right angle, the first cell cut off may be one-third, or 

 even one-half, the original cell. If one-third is cut off, 



