56 MANUAL OF ZOOLOGY. 



in demonstrating in them the existence of cellulose, or of some 

 substance closely allied to cellulose. He has also shown that 

 bodies similar to, if not identical with, coccoliths, occur in forma- 

 tions as old as the Potsdam Sandstone (Lower Silurian) of 

 North America. 



DISTRIBUTION OF FORAMINIFERA IN SPACE. The Foramini- 

 fera are mostly 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 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 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 abund- 

 ance 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 Foraminifer, under the name of Eozoon 

 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 Polytrema 

 and Carpentaria, to both of which, as well as to the extinct 

 Nummulites, it shows a decided affinity. In the Silurian rocks, 

 remains of Foraminifera, some of which are apparently identi- 

 cal with existing forms, have been detected in various places, 



