Pleurobranchus meckeli and P. testudinarius may be killed 

 in chromic acid of 5 per cent. When scarcely dead the animals 

 are transferred to that of 1 per cent, where they may remain 

 from fifteen to sixty minutes, according to their size. The 

 small specimens can be well prepared with chloral hydrate, also, 

 afterwards fixing them with chromic acid of 1 per cent. 



Umbrella is slowly killed in alcoholized sea water, after 

 which it is put into weak alcohol. 



The Elysiidae and the AEolidiidae are permitted to expand 

 in the least practicable amount of sea water. They are then 

 killed by rapidly pouring over them a volume of concentrated 

 acetic acid double or egual to that of the sea water, and when 

 scarcely dead they are transferred to weak alcohol. 



Phyllirrhoe bucephalum is fixed in the chrom-osmic mix- 

 ture for a few minutes or in the chrom-acetic mixture No. 2. 



Doris, Chromodoris, etc. — The larger specimens of these 

 animals may be narcotized by adding 70 per cent alcohol, a little 

 at a time, to the water containing them, until touching the bran- 

 chial appendages on the back produces no contraction. They should 

 then be killed with concentrated acetic acid or boiling saturated 

 sublimate. If cocaine is used for narcotizing the animals, they 

 should be killed in concentrated acetic acid, placed in chromic 

 acid of 1 per cent for ten minutes and then transferred to 50 per 

 cent alcohol, and so on. The small specimens need not be nar- 

 cotized. 



Triopa, Idalia, and Polycera are treated like the Elysiidae, 



The large specimens of Tritonia are immersed until dead in 

 fresh water, to which a few drops of acetic acid have been added, 

 when they are hardened in chromic acid of one-half of 1 per cent. 

 By this method they remain well distended and the shape suffers 

 no alteration. Small Tritonias are treated with cocaine and then 

 hardened and placed in alcohol. 



Marionia is narcotized in alcoholized sea water and killed 

 in acetic acid. 



To prepare Tethys with the dorsal appendages in position, 

 the animal is allowed to expand in a large, low crystallizing dish 

 in the least amount of water possible necessary to cover it. It 

 is killed by pouring over it a quantity of concentrated acetic 

 acid at least as great as the water in the dish. Then the liquid 

 is removed by means of a siphon and chromic acid of 1 per cent 

 substituted therefore. Then carefully try to give the animal a 

 life-like appearance by flattening the foot on the bottom of the 

 receptacle and arranging the cephalic lobe so that it rests easily 

 rolled up in conical shape. In this manner it should harden, 

 and after half an hour the chromic acid should be siphoned off 

 and weak alcohol introduced. The animal must be suspended in the 

 final receptacle. 



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