160 THE MICROSCOPE. 



many as eight of them have been counted in the space of the twelve-hun- 

 dredth of an inch. They are usually found when alive adhering to a 

 branch of some weed that forms the green coating over stagnant waters. 

 They propagate by self-division ; a slight line running down the centre 

 marks where the separation will occur, on each becoming perfectly de- 

 veloped as a distinct object ; and thus from age to age they grow and 

 separate, filling the earth with their flinty shells. The earth found in 

 the river Upper Baun, Ireland, contains an abundance of Gallionella 

 distans, so plentiful in the State of Bilin, and the bergh-mehl of 

 Sweden. 



Gallionella Sulcata is found in many parts of North America ; it 

 somewhat resembles the cylindrical box for spices, which was at one 

 time so common among good housewives ; scientifically, it is described 

 as consisting of chains of cylindrical bivalve loricae, having their outer 

 surfaces marked or furrowed with longitudinal striae ; short joints may 

 occasionally be seen having their ends uppermost, the depth of the 

 furrows being shown on the margin j within the margin is a thin trans- 

 parent rim having radiating striae. Sometimes as many as forty will 

 be found joined together (See Plate II. No. 9). The Gallionella received 

 its designation from a celebrated French naturalist named Gaillon, and 

 is often termed the Box-chain Animalcule; and when the flinty case is 

 seen lying on its face, it much resembles a coin. These animalcules 

 are found in almost all waters, and are stated to be so rapid in their 

 growth, that one hundred and forty millions will by self-division be pro- 

 duced in twenty-four hours. A species named the Striped Gallionella 

 was discovered by Dr. Mantell near London ; the same species is also 

 found in the ocean. Sometimes the chains will be found three inches 

 long ; the size is from the 14th to the 400th part of an inch. 



The beautiful Navicula, or Little Ship, is found in all parts of the 

 world ; and from being met with most readily near London, has been 

 minutely examined and carefully described. Professor Quekett, in the 

 catalogue we have before referred to, describes an " Earth from Bo- 

 hemia, particularly rich in fossil specimens of Navicula viridis, which 

 consists of four prismatic loricse, two ventral and two lateral; the 

 former having round, the latter truncate extremities; and both pro- 

 vided with two rows of transverse markings and dots, longer and 

 more marked on the ventral than on the lateral surfaces. The speci- 

 mens having their ventral surfaces uppermost, exhibit a longitudinal 

 marking in the centre, with a slight dilitation or knob at each extre- 

 mity ; this marking is interrupted in the middle of the lorica, and a 

 diamond-shaped spot is left ; if one of the lateral loricse be examined 



