All the above mentioned deposits are of marine origin, but 

 many others are found at different parts of the world, containing 

 either marine or fresh-water species ; the following are some of 

 these: Bilin, Bohemia; Santa Fiore, Tuscany; Isle de France; 

 polishing slate, Jutland ; New Plymouth, New Zealand ; Soos, 

 near Eger, Bohemia ; several points in Washington Territory and 

 California. Specimens of all of these or any others that may be 

 found are desirable, together with any shells, bones; or other 

 organic remains dispersed through the beds themselves Or the 

 strata above or beneath them, whose position should be mentioned 

 on the label. 



Sub-peat deposits. — These are mostly of a pulverulent charac- 

 ter, when white looking like flour, or when gray, as they com- 

 monly are, like clay. They Occur beneath existing or extinct 

 bogs, ponds, marshes, rivers, and bays. Sometimes the bottoms 

 of ponds are composed of almost nothing but this material. A 

 mass of about six or eight pounds weight should be secured and 

 the same precautions as to keeping separate and labelling speci- 

 mens, adhered to as are given above. As these beds are seldom 

 of any great extent they often become obliterated or covered up, 

 so it will be well to secure a large supply of the material. If any 

 shells are dispersed through it they should be secured along with 

 any overlying peat. These sub-peat deposits have been used as 

 polishing powder, under the name of tripoli; they have also been 

 called shell marl, and are extremely common all over the world, 

 over fifty localities having already been noticed. Specimens from 

 every locality are desirable. 



Muds and deposits from the bottoms of rivers, estuaries, and 

 lakes. — As much as can be conveniently transported, say a large 

 handful, of mud from the bottom of rivers, bays, or creeks, taken 

 at any point below high-water-mark, should be dried without 

 squeezing, and marked as before described. The mud and slime 

 attached to anchors, buoys, and submerged woodwork, together 

 with the scrapings from tlje bottoms of vessels containing shells, 

 plants, zoophytes, &c. can be dried in the same way without any 

 draining. 



Guanos often present us with species of diatoms not otherwise 

 easily obtainable. Quantities of eight or ten pounds weight may 

 be sent in bags made of either stout paper or Backing, the latter 

 material being preferable, with the exaet locality and name of 



