Geological Society. 2G3 



was that the organism depicted by d'Orbigny was doubtfully 

 of Rhizopodal nature, and that it was probably referable to the 

 Ostracoda. The Bpeaker said that he had examined the d'Orbigny 

 type-specimens in Paris in 1914, and had noted that Sotalia dubta 

 was a uiTii and unidentified organism, resembling an Ostracod. 



There the matter rested until Mr. Arthur Karland and the 

 Bpeaker, while examining the material brought by Dr. J. J. Simpson 

 from the Kerimba Archipelago (Portuguese East Africa) in L915, 

 discovered one or two undoubted Poraminifera of an unknown type, 

 which resembled Berthelin's tracing. Prof. Boule kindly sent the 

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

 of Rotalia dubta was established. It is not a Sotalia, 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 sccans (d'Orb.), followed by a 

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

 Biloculina bulloides d'Orb. shows the arrangement of the earlier 

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

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

 Cornuspira foiiacea (Philippi) produced skiagraphs showing the 

 dimorphism of the shells, bothmegalo- and microspheric 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 arena ria Norman shows the internal cavities that 

 ci mtained the protoplasmic body. Two arenaceous forms, Botcllina 

 labyrinihica Brady and Jaculella obtusa Brad}*, 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 Opercidina cornplanata Defrance, the 

 umbilical portion of which is obscured by a mass of secondary 

 shell-suhstance, furnished a clear skiagraph that showed some 

 curious distortions of the internal septa. Similar results were 

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

 species overladen with shell-matter. Cyelammina can cell at a 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 greatlv 



