BY \. MEAD EDWARDS. 



13 



as being more appropriate, :md indicating their most commoD 

 mode of occurrence. In England they are called fossil; but in 



the true acceptation of that term the forms contained in them 

 are not fossils, but are identical with living species. 



They are generally of a pulverulent character, and, when 

 dry, are of little weight, so much so as to attract attention. 

 When free from organic matter, as occasionally occurs, they 

 are quite white, looking almost like powdered starch; but most 

 commonly they are grey, which looks dark while the material is 

 wet, but when dried the color is light. A mass of about six or 

 eight pounds' weight should be secured, and the same precau- 

 tions as to keeping separate and labeling specimens adhered to, 

 as have been already mentioned. As these beds are seldom of 

 any great extent (they often soon become obliterated or covered 

 up), it will be well to secure a good supply of the material while 

 it is accessible. If any shell, wood, or other organic remains 

 should be found dispersed through the deposit, or overlying, or 

 beneath it, they should also be secured, and their position re- 

 corded on the label. Likewise, a sample of any superincum- 

 bent peat should be kept for future examination. In Sweden 

 and Norway, and in Lapland, these deposits have been used 

 to eke out a scanty supply of flour during bad seasons; but they 

 can hardly be said to be food, for they are not nutritious, but 

 most likely only act by their mass distending the stomach, and 

 thus allaying for a time the pangs of hunger. They have like- 

 wise very frequently been employed, under the name of 

 "tripoli," as a polishing material, and are excellent for that 

 purpose. In some parts of this country they go by the name 

 of " marl," but they are not examples of that substance, which 

 is calcareous, being made up of the remains of the shells of 

 mollusca. Specimens from every locality are desirable. 



Muds a,, 'I Deposits from (If I>i,tt<>ms of harbors, bays, lakes, 

 ponds, estuaries <iwl rivers. As a general thing these are not of 



Very great Value to the microSOOpisI for the remains they con- 

 tain, and it is only desirable to collect them in localiti< 

 under circumstances where other gathering cannot be made, or 



when they are known to contain any organisms <>f great heauty 

 or rarity. The blacker and softer the mud the better, for, if it 

 contains much sand or gravel, the minute organisms will be 



