54 collector's manual 



off the mucus sheath with all the sand grains and drop the 

 animals into fixative. This may be 10 percent formalin, which 

 is made up of 1 part of the commercial article in 10 parts of 

 sea or fresh water. Alcohol may serve if nothing else is available. 

 If alcohol is used, kill in 50 percent solution; after 3 to 4 hours 

 transfer to 70 percent and on the following day to fresh 70 

 percent solution. 



In any case change the fluid, preferably twice in the first 24 

 hours, and again after several days. The label should give the 

 locality, date, color, method of preservation, and name of 

 collector. 



Some technicians may have facilities available for preparing 

 Bouin's Picro-formol fluid for a fixative. This is made as follows: 

 Picric acid, saturated - aqueous solution, 75 parts; formol 25 parts; 

 acetic acid 5 parts. Place the specimens in Bouin's Picro-formol, 

 change to 50 percent alcohol after first day, and to 70 percent 

 alcohol on third daj r for preservation. 



MOLLUSKS 



Mollusks may be found almost everywhere. Some live in the 

 tops of tropical forest trees, others in shrubbery, and still others 

 on the ground, in lakes and streams, and in the sea, where they 

 range from the shore line to great depths. Full-grown mollusks 

 vary in size from that of a pin head to a weight of 700 pounds. 

 The smaller species are the least known and therefore the 

 most interesting. 



The group is divided into five classes: bivalves (fig. 38), 

 snails (fig. 39), tooth shells (fig. 40), coat-of-mail shells (fig. 41), 

 and cephalopods (fig. 42). 



