Reports & Proceedings — Geological Society of London. 91 



resembled Berthelin's tracing. Professor Boule kindly sent the 

 d'Orbigny type-specimen to London, and the Rhizopodal nature of 

 Rotalia dubia was established. It is not a llotalia, and it must 

 await determination until more specimens are obtained. It has been 

 named provisionally Pegidia papillata. There were two or three 

 forms of the organism, but only one perfect specimen of the 

 d'Orbigny type ; and it was undesirable to risk destruction by 

 cutting a section, of it. In these circumstances Mr. Barnard was 

 approached, and he experimented with the object of ascertaining the 

 interior structure of the shell by means of the X-rays. His results 

 were extraordinarily promising, and led to further experiments. 



The speaker showed on the screen photographs of the common 

 and dense Foraminifer Massilina secans (d'Orb.), followed by a 

 skiagraph of the same. A skiagraph of the still denser test of 

 BiloGulina hulloides, d'Orb., shows the arrangement of the earlier 

 chambers as clearly as it is indicated in Schluraberger's beautiful 

 sections. The application of X-rays to the dense imperforate shells 

 Cormispira foliacea (Philippi) produced skiagraphs showing the 

 dimorphism of the shells, both megalo- and mici'ospheric primordial 

 chambers being clearly distinguishable. Such results led to the 

 extension of the experiments to the agglutinated arenaceous forms, 

 of which sections are made with extreme difficulty. The skiagraph 

 of Astrorhiza arenarta, Norman, shows the internal cavities that 

 contained the protoplasmic body. Two arenaceous forms, Botellina 

 labyrinthica, Brady, and Jaculella obtusa, Brady, that are almost 

 identical in external appearance, are distinguished at once by their 

 respective skiagraphs, the one exhibiting a simple tubular cavity, 

 the other appearing labyrinthic. 



Mr. Barnard subsequently experimented on still more difficult 

 material. The massive Operculina complanata, Defrance, the 

 umbilical portion of which is obscured by a mass of secondary 

 shell-substance, furnished a clear skiagraph that showed some 

 curious distortions of the internal septa. Similar results were 

 obtained in the case of Orbiculina adimca (Fichtel & Moll), another 

 species overladen with shell-matter. Cyclammina cancellata, Brady, 

 is an arenaceous form, composed of softer mud and sand, studded 

 with coarse sand-grains, which make section-cutting almost an 

 impossibility. The skiagraphs, however, reveal the primordial 

 chamber and establish the character of this form. 



The determination of the Nummulites, depending as it does on 

 a knowledge of the internal structure of the test, is greatly facilitated 

 by the application of X-rays, which removes the necessity of splitting 

 it or cutting sections through it. 



The speaker showed ordinary photographs and skiagraphs, made 

 at slightly varying azimuths, of Nummulites Imvigata and N. vario- 

 laria, forms that strew the shores of Selsey Bill. A particularly 

 notable result was obtained in the case of N. ghehensis, an organism 

 that forms the dense masses of Nummulitic limestone of which the 

 Pyramids of Egypt and the Citadel at Cairo are built. 



Mr. Barnard said that, although the utilization of X-rays to 

 determine the internal structure of various bodies was well known. 



