RHIZOPODA. 37 



ondly, that life is the cause of organization, and not the result of it : in other 

 words, an animal is organized, or possesses structure, because it is alive ; it 

 does not live because it is organized. 



DISTRIBUTION OF FORAMINIFERA m SPACE.* The Foraminifera are ex- 

 clusively marine or inhabitants of the ocean, and have a world-wide distribu- 

 tion. They are mostly very minute, but some of vhe extinct forms attained 

 a size of as much as three inches in circumference (e. g., the Nummulite, 

 Fig. 5). Some forms may be obtained adhering to the roots of tangle (Lami- 

 niria) at or near low-water mark, but they are mostly to be dredged from tol- 

 erably deep water. In the deepest parts of the ocean which have yet been 

 examined by the dredge at a depth, namely, of nearly three miles Forami- 

 nifera have been obtained in abundance. There is also no doubt that in 

 many parts of the deep ocean, especially where warm currents exist, there 

 are now forming deposits of the shells of Foraminifera, which may well be 

 compared to the great masses of white chalk with which the geologist is 

 familiar. Foraminifera may generally be obtained for examination from the 

 shakings of sponges or from the sand of the sea-shore, especially in warm 

 climates. To give some idea of their abundance, it may be stated that Plan- 

 cus found about 6,000 specimens in an ounce of sand from the Adriatic ; but 

 D'Orbigny calculated that no fewer than between three and four millions 

 were present in an ounce of sand from the Caribbean Sea. 



DISTRIBUTION OF FORAMINIFERA IN TIME. It is not the object of the 

 present work to enter into the consideration of the past existence of differ- 

 ent groups of animals, since this presupposes some knowledge of geology, 

 but the Foraminifera present some points of special interest which may be 

 very shortly noticed. In the first place, as far as is yet known, the Forami- 

 nifera were the earliest and oldest of created beings. The oldest fossil 

 which has hitherto been exhumed by the labors of geologists is believed to 

 have been a Foraminifer, \ of large size, and with some decided affinities to 

 existing forms. In the second place, it is only by an examination of the dis- 

 tribution of the Foraminifera in past time that we can arrive at any ade- 

 quate notion of the importance of these microscopic creatures when looked 

 at in the aggregate. The great geological formation known as the white 

 chalk a formation which forms the well-known chalk-cliffs of the south of 

 England, and which stretches over a great part of the continent of Europe, 

 attaining sometimes a thickness of not less than 600 feet is almost wholly 

 composed of the shells of Foraminifera, visible only to the microscope. The 

 smallest fragment of the common chalk, with which every one is familiar, 

 contains numbers of these minuta shells ; and it is a singular fact that some 

 of the species in the chalk are indistinguishable from forms which now oc- 

 cur in the ooze which forms the bed of the Atlantic at great depths. The 

 stone of which Paris is built is to a very great extent composed of the shells 

 of Foraminifera, especially of the Miliola ; and it is hardly an exaggeration 

 to say that Paris is mainly built up out of these minute organisms. Another 

 remarkable formation is that known as the " Nummulitic limestone," from 

 the presence in it of a large coin-shaped Foraminifer, the Nummulite (Fig. 

 5), generally about as large as a shilling. 



The Nummulitic limestone stretches from France on the west to the fron- 

 tiers of China on the east, and is almost everywhere readily recognizable as 



* Under the term " Distribution in Space" come all the facts relating to the present 

 occurrence of any animal or group of animals upon the globe. Under the term " Distribu- 

 tion in Time " come all the facts relating to the past occurrence of any animal or group of 

 animals upon the globe. 



t The Eozoon Canadense of the Laurentian Eocks of Canada. 

 3 



