THE PRESERVATION OF MARINE OBJECTS 81 



it turns the shells of some crustaceans red, making them appear as 

 if they had been boiled. 



Other crustaceans are so small, or are hardened externally to 

 such a slight extent, that they also are not adapted for the dry 

 method of preservation. Speaking generally, such crustaceans as 

 shrimps and sand-hoppers are best preserved in fluid, while the 

 different species of crabs and lobsters are more conveniently pre- 

 served dry unless it is desired to study any of their soft structures. 



It is quite impossible to remove the soft parts from small crabs 

 and lobsters previous to drying them, hence the drying should be 

 conducted as rapidly as possible, so that no decomposition may 

 set in. Where the process goes on very slowly, as is the case when 

 the air is damp, or when the specimens are not set out in an airy 

 spot, a decay of the soft structures soon proceeds, and the products 

 of this decay will generally saturate the whole specimen, giving rise 

 to most objectionable odours, and destroying the natural colour of 

 the shell. 



If it has been found that the species in question are not reddened 

 by the action of methylated spirit, they should be allowed to remain 

 in this fluid, with a few grains of dissolved corrosive sublimate, for 

 at least a few hours, and then they will dry rapidly without any 

 signs of putrefaction; and even those species that are reddened 

 by spirit may be treated to a shorter immersion in this fluid with 

 advantage. 



The specimens should always be set out in some natural attitude 

 to dry, unless it is desired to spread out the various appendages in 

 some manner that is more convenient for the study of their structure. 

 A sheet of blotting-paper may be placed on cork or soft wood, the 

 specimens placed on this, and the appendages kept in the desired 

 positions when necessary by means of pins placed beside, but not 

 thrust through them. When more than one specimen of the same 

 species has been collected, one should be set in such a manner 

 as to exhibit the under side ; and, further, in instances where the 

 male and female of the same crustacean differ in structure, as is 

 commonly the case, two of each should be preserved, one displaying 

 the upper, and the other the under surface. 



When perfectly dry, all small crustaceans should be mounted 

 on cards with the aid of a little gum, and the name and other 

 particulars to be remembered then written on the card. 



The question may well be asked : ' Which is the best gum to 

 use ? ' In answer to this we may say that gum tragacanth is 



o 



