NATURAL HISTORY OF THE DIATOMAECjE. 483 



adherent to marine shells, which are commonly removed by students of 

 conchology, have often been found to yield rich harvests of rare forms of 

 diatomaceae. Such material can be washed, or, still better, scraped off of 

 the living or dead shells (the dirtier such shells seem the better, of course), 

 placed in paper and plainly labelled with the exact locality, and, if possi- 

 ble, name of the shell and depth of water from which it was taken. Con- 

 chologists will do well to save all their shell-cleanings for this purpose. 



Marine Invcrtcbrata. Specimens of the entire animal, or the contents 

 of the stomachs of echinoidea (sea urchins) and holothuroidea (sea cu- 

 cumbers), should be secured, as it has been found that many, if not most 

 of them, are vegetable feeders, and thus take into their stomachs algae 

 which have diatomaceae growing upon them. The entire animal should 

 be preserved in spirits (if alcohol is not procurable, brandy or whiskey 

 will answer), but if that be not convenient, they, as well as the contents 

 of the stomachs, may be dried without washing in any way. It has been 

 found that holothurians, when they are immersed in spirit, often turn 

 their stomachs inside out, and thus the contents, which are the part most 

 valuable for the microscopic organisms, will be found at the bottom of 

 the containing vessel. When the whole animal is preserved in spirit, the 

 label may be written in ink on stiff paper or parchment, and, when quite 

 dry, tied to the specimen and immersed with it in the spirit. In this way 

 several specimens can be preserved in the same vessel, and space econo- 

 mized. This method will be found to be the best, as labels pasted or 

 gummed on, or otherwise attached to the vessel, are liable to be obliter- 

 ated from leakage of the contained fluid, or removed during transporta- 

 tion. The stomachs of mollusca (shell fish) and crustaceans (lobsters, 

 crabs) also occasionally yield specimens of diatomaceae, and it will be 

 well to secure specimens of those creatures in the manner described. 

 The stomachs of fish occasionally contain diatomaceae, and may be 

 secured. 



Soundings. The material brought up from the ocean bed by the 

 sounding-line, or the larger masses procured by means of the dredge, 

 have been found to yield good returns of microscopic treasures when 

 examined. The calcareous shells of foraminifera, as well as siliceous 

 polycystina and diatomaceae, are found in them. When kept for this 

 purpose, note should be made of the latitude and longitude, depth of 



