90 Reports & Proceedings — Geological Society of London. 



being more in the nature of impregnations of the country rock, but 

 the mineral assemblage is similar and is obviously derived from the 

 same magma, perhaps at a slightly later date, when differentiation had 

 proceeded further. At a still later stage there seems to have been 

 a good deal of secondary enrichment by sulphides and chlorides. 



This area forms an excellent example of the metasoraatic type of 

 vein deposit, including both sulphidic and oxidic ores. The 

 connexion between the mineral veins and the granitic intrusions is 

 particularly clear, and the mineral association is of a distinctive and 

 peculiar character. 



R. H. E. 



I. — Geological Society op London. 



1. December 5, 1917.— Dr. Alfred Harker, r.E..S., President, in the 



Chair. 



A demonstration on the application of X-rays to the determination 

 of the interior structure of microscopic fossils, particularly with 

 reference to the dimorphism of the Nummulites, was given by 

 E. Heron-Allen, F.L.S., F.G.S., Pres.R.M.S., and J. E. Barnard, 

 E.ll.M.S. 



Mr. Heron-Allen said that in the year 1826 Alcide d'Orbigny 

 published among the innumerable, and for many years unidentified, 

 nomina niida that compose his "Tableau Methodique de la Classe 

 Cephalopodes " the name Rotalia dubia. This species was left 

 untouched by Parker & Jones in their remarkable series of articles 

 " On the Nomenclature of the Foraminifera". The French naturalist 

 G. Berthelin was the first investigator to unearth and make use of 

 the "Planches inedites" which had been partly completed by 

 d'Oi'bigny for the illustration of his great work upon the Foraminifera, 

 a work that was never published. Working with Parker & Jones's 

 paper, Berthelin made for his own use careful tracings of 246 of 

 A. d'Orbigny's unfinished outline sketches. These sketches were 

 never elaborated by d'Orbigny upon the " Planches", which are'still 

 preserved in the Laboratoire de Paleontologie under the care of 

 Professor Marcellin Boule ; among them was found the sketch of 

 Rotalia dubia. On the death of Berthelin the tracings passed into the 

 possession of Professor Carlo Fornasini, of Bologna, who reproduced 

 them all in a valuable series of papers published between the years 

 1898 and 1908. Fornasini's opinion was that the organism depicted 

 by d'Orbigny was doubtfully of Bhizopodal nature, and that it was 

 probably referable to the Ostracoda. The speaker said that he had 

 examined the d'Orbigny type-specimens in Paris in 1914, and had 

 noted that Rotalia dubia was a worn and unidentified organism, 

 resembling an Ostracod. 



There the matter rested until Mr. Arthur Earland and the speaker, 

 while examining the material brought by Dr. J. J. Simpson from the 

 Kerimba Archipelago (Portuguese East Africa) in 1915, discovered 

 one or two undoubted Foraminifera of an unknown type, which 



