. Elements of comparative zoology. Zoology. 148 SYSTEMATIC ZOOLOGY. move about and obtain their food. The subdivisions of the class are based primarily upon the character of the pseudo- podia. Order I. Lobosa. With broad pseudopodia few in number. Best known is the genus Amoeba of fresh water. Other genera have shells (fig. 3).. ;v££ Fig. 3.—Difflugia. A lobose Rhizopod with a shell of grains of sand. Common in fresh water. Fig. 4. — Foraminifera. extended pseudopodia chambered shell of Globigerina. A, Biloculina with (after Schultze); B, Order II. Foraminifera. Numerous slender pseudopo- dia
. Elements of comparative zoology. Zoology. 148 SYSTEMATIC ZOOLOGY. move about and obtain their food. The subdivisions of the class are based primarily upon the character of the pseudo- podia. Order I. Lobosa. With broad pseudopodia few in number. Best known is the genus Amoeba of fresh water. Other genera have shells (fig. 3).. ;v££ Fig. 3.—Difflugia. A lobose Rhizopod with a shell of grains of sand. Common in fresh water. Fig. 4. — Foraminifera. extended pseudopodia chambered shell of Globigerina. A, Biloculina with (after Schultze); B, Order II. Foraminifera. Numerous slender pseudopo- dia which branch and unite to form networks. Nearly all are marine. Most species form calcareous shells which in many species increase with growth by adding addi- tional chambers to the original one. There is a terminal aperture for the extension of the pseudopodia and in many minute pores through the sides of the shell. These forms occur in large numbers in certain seas and the dead shells are forming thick layers at the bottom of the ocean. They have done the same in ages past and in various parts of the earth are thick beds of limestone largely built up from their dead shells. Indeed they are the largest contributors to the formation of rock of all Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Kingsley, J. S. (John Sterling), 1854-1929. New York, H. Holt and Company
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