BULLETIN 39, UNITED STATES NATIONAL MUSEQM, [22] 



considerable water will have gone over with the animals. After fifteen 

 minutes wash in fresh water and transfer to 35 per cent alcohol. Still 

 another method is to use the chrom-osmic acid mixture as a hardening 

 medium, but the animals do not remain as transparent and the tentacles 

 are somewhat contracted. 



During the hardening process, especially when many of the medusae 

 are treated at the same time, the tube should be held in a horizontal 

 position in such a way that the bells are down on the side of the tube 

 and the animals not in contact. For the final preservation of certain 

 forms (like Lizzia) place them in alcohol in a small tube, separating 

 the individuals by wads of cotton, and put this into the exhibition jar. 



Oceania conica and Tiara pileata are narcotized in alcoholized sea 

 water (3 j)er cent) and then treated like the preceding. 



MEDUSA FORMS OF THE CAMPANULARID^. 



Uucope, Gastrohlasta, and Obelia are fixed in the mixture of sulphate 

 of copper and sublimate and after a few minutes are washed in fresh 

 water until every trace of precipitate has vanished, and tlien placed in 

 weak alcohol, and so on. 



Mitrocoma and JEquorea are killed with acetic acid and immediately 

 transferred to the chrom-osmic mixture, where they may lie from fifteen 

 to thirty minutes, according to their size. Small specimens ol, JEquorea 

 can be placed at first in the chrom-osmic mixture. 



Tima flavilahris is best preserved by killing in formalin of 4 per 

 cent, where it may remain from five to twenty days, if desired, before 

 the transfer to alcohol begins. This transfer must be made very grad- 

 ually. The older method of treatment is to kill the animal with 

 chromic acid of T) per cent in volume equaling that of the water in which 

 it is, and after five minutes to transfer it to the chrom-osmic mixture. 

 After half an hour in the latter mixture wash in fresh water and trans- 

 fer to alcohol. This method stains the animal brown, while that with 

 formalin leaves it colorless. 



OUndias miilleri. — The old method is to kill with acetic acid and 

 immediately transfer to chromic acid of 1 per cent, where the marginal 

 tentacles are to be stretched out by means of a pair of forceps, and 

 where the animals may remain about a quarter of an hour before they 

 are removed to the weak alcohol. The new and more satisfactory 

 method is to place them bottom side up in a shallow tray partly filled 

 with sea water and suddenly pour over them a volume of G per cent 

 formalin equal to that of the water in the tray. In the 3 per cent 

 solution of formalin thus made they are to remain at least a week 

 before they are removed to 35 per cent alcohol, and gradually thereafter 

 to 70 per cent alcohol. 



Trachymedusw. — Bhopalonema, Cunina, ^gineta, JEginopsis, Liriope, 

 and Carmarina are fixed in the chrom-osmic liquid for five to twenty 

 minutes, according to their size, washed in fresh water, and gradually 



