in a mixture of sea water and fresh water in equal parts, and after- 

 wards killing them with acetic acid. This may be used for prepar- 

 ing several species of Nassa, Columbella, Conus, and Trochus. 



Heteropoda. — The Atlantidae may be narcotized in alcoholi- 

 zed sea water, where they are allowed to remain for from six to 

 twelve hours, and are then placed directly in alcohol. Cocaine, 

 however, is much better for narcotizing. 



The Pterotrachaidae are killed by immersing them in chrom- 

 acetic mixture No* 1 for from ten to thirty minutes according to 

 their size. Wash thoroughly in fresh water and transfer gradually 

 to the different grades of alcohol. These animals are well pre- 

 pared also with the chrom-osmic mixture, and the little specimens 

 of Carinaria are best treated with the mixture of sulphate of copper 

 and sublimate. Large specimens should be suspended in the perma- 

 nent receptacle by a thread tied around the end of the proboscis. 



Opisthobranchiata. — The Bullas are slowly narcotized in the 

 mixture of sea water and fresh water in equal parts or in alcohol- 

 ized sea water and allowed to remain therein until thoroughly 

 insensible. They are killed with concentrated acetic acid and 

 transferred at once to alcohol. 



Gastropteron meckeli is killed in Kleinenberg ' s solution, 

 thereby retaining its natural red color very well. It looses its 

 color in the ordinary liquids. 



Doridium and Scaphander. — Narcotize in alcoholized sea 

 water, kill in concentrated acetic acid, and quickly transfer 

 to alcohol. If not hard enough, or if softened at all in the 

 acetic acid, they may be placed in chromic-acid solution of 1 

 per cent for ten or fifteen minutes before they are put into 

 alcohol. 



Philine. — When the animal is well distended in a little 

 sea water, suddenly pour over it concentrated acetic or pyrolign- 

 eous acid and quickly transfer to alcohol. 



Pleurophyllidia is narcotized with alcoholized sea water 

 and then killed with concentrated acetic acid. 



Aplysia limacina and A. punctata are fixed in 1 per cent 

 chromic acid, where they are allowed to remain from fifteen to 

 sixty minutes, according to their size. A. depilans is narcotized 

 in chloral hydrate solution of 1 per cent (whxch may take twelve 

 hours) , killed with concentrated acetic acid, transferred at once 

 to chromic acid of 1 per cent, and after half an hour put into 

 50 per cent alcohol, and so on. 



Pleurobranchia meckeli is best treated with cocaine and 

 then put into chromic acid of 1 per cent, where the animals may 

 remain about an hour before they are washed and put into alcohol. 



- 43 - 



