A guide to the fossil invertebrate animals in the Department of geology and palaeontology in the British museum (Natural history) . p in them and taken into the central body at any Protozoa are called Gymnomyxa (naked slimes) orRhizopoda (root-feet). They may be divided into theClasses : I. Lobosa, with lobose pseudopodia, Amoeba,II. Heliozoa or Sun Animalcules, with fine radiating pseudo-podia. III. Foraminifera, with pseudopodia branching andagain uniting so as to form a network. IV. Radiolaria,with fine radiating pseudopodia, as in Heliozoa, but withthe central protoplasm e
A guide to the fossil invertebrate animals in the Department of geology and palaeontology in the British museum (Natural history) . p in them and taken into the central body at any Protozoa are called Gymnomyxa (naked slimes) orRhizopoda (root-feet). They may be divided into theClasses : I. Lobosa, with lobose pseudopodia, Amoeba,II. Heliozoa or Sun Animalcules, with fine radiating pseudo-podia. III. Foraminifera, with pseudopodia branching andagain uniting so as to form a network. IV. Radiolaria,with fine radiating pseudopodia, as in Heliozoa, but withthe central protoplasm enclosed in a porous membrane orcapsule. In each of these groups there are some generathat construct a skeleton and others that do not; but in the 16 GUIDE TO THE FOSSIL INVEETEBEATE ANIMALS. Gallery X. Lobosa and Heliozoa such genera are few, and their remainshave not been found in any rock. In the Eadiolaria, on theother hand, the large majority form a skeleton, while in theEoraminifera there are very few without it well two groups, therefore, are abundantly represented inthe fossil state. Class Fig. 1.—Living Foraminifera, with extended pseudopodia, some of whichmay be supposed to stretch far beyond the limits of the page, a is anImperforate Foraminifer, Miliola tenera, the nucleus (darkly shaded)and the surrounding protoplasm, with its bubbles, prevent the innerchambers from being seen. & is a Perforate Foraminifer, Botaliaveneta, and shows the pores through which the pseudopodia stretchon all sides. Both enlarged 36 diameters. (Modified from M. , 1854.) or test. Sometimes, especially in fresh-water species, the shellconsists only of chitin, and then is never found fossil. Inseveral a chitinous or thin calcareous coat is strengthened bygrains of sand or other foreign particles, as is the case of acaddis-worm, and some tests of this arenaceous composition PKOTOZOA—FOEAMINIFERA. 17 are preserved in the rocks. This shell encloses the
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