1909-1910.] 



293 



" FORAMINIFERA." 



A meeting of the Club's Geological Section was held in the 

 Museum, on 15th December, Mr. W. J. C. Tomlinson presiding, 

 when Mr. Joseph Wright, F.G.S., gave a most interesting demon- 

 stration on that group with which his name is inseparably 

 connected. 



Mr. Wright began his lecture by describing the Foraminifera 

 as belonging to the lowest type of animal lite, and forming an 

 important group of the Protozoa, characterised by their great 

 simplicity of structure. He pointed out at the same time the 

 important part Foraminifera play in building up the sedimentary 

 formations of the earth by secreting carbonate of lime from the 

 ocean, and how their work is still being carried on over large areas 

 of the ocean floor, where, intermixed with coccoliths, they form 

 the globigerina oose. It owes its name to the large proportion of 

 shells of Globigerina bulloides and other pelagic Foraminifera. 

 The Foraminifera are usually very minute, though some genera, 

 such as Nummuiiies, attain a considerable size. They are 

 found in sea water from great depths to between high and low 

 water mark, but often the same form is obtained of larger size in 

 the deeper water. The body substance is composed of sarcode, 

 which gives out long thread like processes (pseudopodia) ; these 

 interlace and form a net-work of filaments reaching the exterior 

 by perforations in the shell, or by the mouth. The lecturer then 

 described the classification according to shell texture — ( 1 ) Porcell- 

 aneous, white and glazed like porcelain ; (2) Arenaceous, sand or 

 other foreign material included in the test ; (3) Subarenaceous ; 

 (4) Hyaline, clear like glass. Fossil Foraminifera, he stated, 

 are found in nearly all sedimentary rocks from Silurian to 

 sub-recent formations. He cited Fusulina and Saccamina as 

 important rock builders of the Carboniferous series, Giobigeritia 

 of the Chalk and recent ooze, and Nummulites of the Tertiary 

 strata. Some forms, such as Nodosaria, being very persistent 

 through long periods. The lecturer then explained "Isomorphism" 



