16 GUIDE TO THE FOSSIL INVEETEBEATE ANIMALS. 



Gallery X. Lobosa and Heliozoa such genera are few, and their remains 

 have not been found in any rock. In the Eadiolaria, on the 

 other hand, the large majority form a skeleton, while in the 

 Eoraminifera there are very few without it well developed. 

 These two groups, therefore, are abundantly represented in 

 the fossil state. 



Class FORAMINIFERA. 



Fig. 1. — Living Foraminifera, with extended pseudopodia, some of which 

 may be supposed to stretch far beyond the limits of the page, a is an 

 Imperforate Foraminifer, Miliola tenera, the nucleus (darkly shaded) 

 and the surrounding protoplasm, with its bubbles, prevent the inner 

 chambers from being seen. & is a Perforate Foraminifer, Botalia 

 veneta, and shows the pores through which the pseudopodia stretch 

 on all sides. Both enlarged 36 diameters. (Modified from M. S. 

 Schultze, 1854.) 



or test. Sometimes, especially in fresh- water species, the shell 

 consists only of chitin, and then is never found fossil. In 

 several a chitinous or thin calcareous coat is strengthened by 

 grains of sand or other foreign particles, as is the case of a 

 caddis-worm, and some tests of this arenaceous composition 



