22 GUIDE TO THE FOSSIL INVERTEBRATE ANIMALS. 
Gallery X. 
Table-ease 
16 . 
Tlie marine Eoraminifera, witli wliich ceologists are 
chiefly concerned, are found on sea-weed and similar objects 
on tiie sea-floor, from shore pools down to great de|)ths, and 
from arctic to tropical waters, sometimes fixed and some- 
times free ; they live chiefly on diatoms and algae. l\Iost 
of the Globigerinidae fl(jat in the warm surface-water of the 
great oceans down to a de])th of 500 fathoms, and stretch 
out their pseudopodia along delicate spines ; these eat also 
minute animals. 
The em])ty shells are found in all kinds of marine 
deposits. Numbers are drifted ashore, as at I’ochelle and 
at Dog’s Bay, Connemara, whence 124 kinds have been 
Fio. 4. — Foraniinifera as lloek-fonuers. o, Globigerina Ooze, from a depth 
of 2,760 fathoms in the North Atlantic, x 24 diameters. b, Forami- 
nifera washed from Chalk rock near Dunstable, x 36 diameters. 
(From Chapman’s “ Foraniinifera.” By permission of Messrs. 
Longmans.) 
obtained. An ounce of sand from the Adriatic yielded 
G,000 shells. Deposits dredged from the sea-bottom contain 
each a special assemblage varying with the nature of the 
bottom, depth, and temperature. Such are the coral sands 
of the Pacific, and the greensands formed at about 500 
fathoms. In the latter the empty shells become filled with a 
green siliceous mineral (glauconite) and often disajipear, 
leaving their casts behind. In the deeper parts of the ocean, 
especially where the surface is warm, is found an ooze 
mainly consisting of the shells of Globigerinidae and other 
pelagic forms (Fig. 4 a); its extent is estimated at 49 
milli )u square miles, and its thickness must he enormous. 
It is natural, therefore, that Foraniinifera should not 
