92 W. B. CARPENTER ON THE STRUCTURE OF ORBITOLTTES. 



In the first place, the group of organisms, which includes the genus 

 Orbitolites, had been long known as fossils, some species occur- 

 ring in great numbers. Indeed, nearly all the building stone in 

 Paris is an early Tertiary limestone composed almost entirely of 

 Miliolines; and in the same limestone were elsewhere found a number 

 of discs about the size of a fourpenny piece, which had attracted 

 some notice. They were mentioned by Lamarck, who considered 

 them as Polypi, and placed them between Lunulites and Millepores. 

 This is not very surprising, because their surfaces are for the most 

 part abraded and laid open ; but no suspicion seems to have arisen 

 that they were anything else than Polypi. In the later edition of 

 Lamarck, it was said that forms similar to these had been dis- 

 covered in a living state on the west coast of Australia; a small 

 species was also found living in the Mediterranean, but this was 

 of almost microscopic size. It was my good fortune to come into 

 possession of some specimens of these recent discs about 40 years 

 ago ; they were given to me by my friend Prof. Ed. Forbes, who 

 obtained them from Mr. Jukes, who had dredged them up off the 

 coast of Australia. I had at that time been examining Nwnmu- 

 lites, which were the first Foraminifera to which I gave continuous 

 attention, and of which I had received clay- embedded specimens 

 from Dr. Bowerbank. (I found that these gave generally much 

 better microscopic structure than Nummulites from any other 

 bed would afford ; for when massed together in Nummulitic 

 limestone, the percolation of water through the calcareous matrix 

 fills up the tubes and alters the texture to such a degree that it 

 is a matter of difficulty at times to recognise them ; whilst those 

 from the clay give the structure with a perfection scarcely ex- 

 ceeded by recent specimens. This I have since found to hold 

 good in many other cases.) 



I was especially on the outlook for anything which would 

 elucidate the structure of some small discs obtained from a moun- 

 tain near Biarritz, which was described to me as almost entirely 

 made up of them. For a long time I could not find anything like 

 them ; but happening to ask Prof. Forbes if he could throw any 

 light on the matter, he at once put Mr. Jukes' specimens into my 

 hands.* This was the beginning of my study of the Foraminifera ; 



* The Biarritz discs subsequently proved to possess a very different 

 internal structure, which I have described as characterizing D'Orbigny's 

 genus Orbitoides. 



