File:A guide to the fossil invertebrate animals in the Department of geology and palaeontology in the British museum (Natural history) (1907) (14592500069).jpg

Identifier: guidetofossilinv00brit (find matches)
Title: A guide to the fossil invertebrate animals in the Department of geology and palaeontology in the British museum (Natural history)
Year: 1907 (1900s)
Authors: British Museum (Natural History). Dept. of Geology Bather, Francis Arthur, 1863-
Subjects: Fossils
Publisher: London, Printed by order of the Trustees
Contributing Library: Smithsonian Libraries
Digitizing Sponsor: Biodiversity Heritage Library

View Book Page: Book Viewer
About This Book: Catalog Entry
View All Images: All Images From Book
Click here to view book online to see this illustration in context in a browseable online version of this book.

Text Appearing Before Image:
p in them and taken into the central body at any point.These Protozoa are called Gymnomyxa (naked slimes) orRhizopoda (root-feet). They may be divided into theClasses : I. Lobosa, with lobose pseudopodia, e.g. 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 developed.These two groups, therefore, are abundantly represented inthe fossil state. Class FORAMINIFERA.
Text Appearing After Image:
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. S.Schultze, 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 main ^^H^^ymass of protoplasm, but the pseuclopodia stretch out throughcertain openings. Either they are confined to the apertu

Note About Images