XIV 
TABLE OF CONTENTS. 
Page. 
2.. . . 
Pyxidicula. 
Gaillonclla. 
Actinocyclus. 
Coscinodiscus. 
Navicula. 
Eunotia. 
Cocconeis.. ’^4 
Bacillaria. 
Tessella. 
Fragillaria . 
Meridion. 
3. Echinellea .. 238 
Isthmia.238 
Synedra. 238 
Padasphenia. 239 
Gomphonema. , . 239 
Echmella. 240 
Cocconema. 240 
Achnanthes. 241 
Striatella. 241 
4. ’Lace.rnatoj . 242 
Triostulia . . 242 
Syncyclia. 242 
Naunema. 242 
GJo3onema.. 243 
Schizonema. 243 
Geological effects of these microscopic animals. 77 
Source of the silex of their shells. 77 
Lime of testacea, whence derived. 77 
Lime of eggs of birds and of coral, phosphate of lime of animals, etc. deduced, 78 
Lime, etc. of animals not formed by animal secretion, but secreted from their 
food and from water. 78 
Alluvions from solution . 79 
1. Calcareous alluvions. 79 
Tufa, stalactites, stalagmites, sinter, tufaceous marl. 80 
Localities of these alluvions. 80 
Clay balls and calcareous concretions. 82 
Causes of these concretions... 82 
2. Sulphates of lime, alumina, etc. and localities. 83 
3. Nitrates of lime and potassa. 85 
4. Sulphate of magnesia, and muriates of soda and lime.. 86 
