PROTOZOA : FORAMINIFERA. 65 



in demonstrating that bodies similar to, if not identical with, a*w/zV/b, occur 

 in formations as old as the Potsdam Sandstone (Lower Silurian) of North 

 America. More recently still, Mr Carter has shown that coccoliths occur 

 in great numbers in the Laminarian zone, and he asserts them to be solitary, 

 unicellular, calcareous Alga. He describes them under the name of 

 Melobesia unicellularis and M. discus, according as they are oval or round ; 

 and he believes that the coccospheres are most probably their "sporangia." 

 Upon this view the term ''coccoliths" would be restricted to the fossil 

 forms. 



DISTRIBUTION OF FORAMINIFERA IN SPACE. The Forami- 

 nifera are marine, and are found in almost all seas, though 

 more abundantly in those of the warmer parts of the globe. 

 It is concluded by Dr Carpenter that " the foraminiferous 

 fauna of our own seas probably presents a greater range of 

 variety than existed at any preceding period ; but there is no 

 indication of any tendency to elevation towards a higher type." 

 One of the most remarkable facts about their distribution at 

 the present day, is the existence of a deposit at great depths 

 in the Atlantic, but only in areas traversed by heated currents, 

 formed almost entirely of the shells of Foraminifera, and very 

 closely resembling chalk. It has further been quite recently 

 established that there coexist with these Foraminifera various 

 animals of a higher grade, some of which closely resemble, or 

 are even specifically inseparable from, well-known Cretaceous 

 species. There is therefore some reason to conclude that the 

 bottom of the sea at great depths is peopled at the present day 

 by a fauna which is very closely allied to that of the Chalk. 

 Most living Foraminifera are very minute, but some of the 

 extinct forms attained the size of as much as three inches in 

 circumference (e.g., the Nummulite, fig. 9), and spheres of 

 Parkeria may attain a circumference of nearly eight inches. 

 Some forms may be obtained adhering to the roots of tangle 

 at or near low-water mark, but they are mostly to be dredged 

 from tolerably deep water. They have been found, in fact, in 

 great abundance in the deepest parts of the ocean which have 

 as yet been examined by the dredge at a depth, namely, of 

 nearly three miles. 



DISTRIBUTION OF FORAMINIFERA IN TIME. Remains of 

 Foraminifera have been found in Palaeozoic, Mesozoic, and 

 Kainozoic formations. In the oldest stratified rocks with which 

 we are acquainted viz., the Laurentian rocks of Canada- 

 there occurs a singular body which has been described as the 

 remains of a gigantic Foraminifera, under the name of Eozob'n 

 Canadense. If truly organic, as is doubted by some, it is the 

 oldest fossil as yet discovered. It appears to have grown 

 in reef-like masses resembling the sessile patches of Poly- 



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