864 . The American Naturalist. | iiber, 
of the valves of Lamellibranchs on immersion in 70 per cent. alcohol, 
little plugs of wood should be placed between the margins of the 
valves. The same result may be effected in the case of Prosobranchs 
by tying the internal edge of the operculum to the shell. 
Of the Opisthobranchs the æolidæ may be best preserved by pour- 
ing over them concentrated acetic acid in volumes equal to or double 
that of the sea-water containing them. Dorids should first be narcot- 
ized by gradually adding 70 per cent. alcohol to their sea-water, and 
then killed with concentrated acetic acid or boiling sublimate. The 
larger forms may be killed in 1 to 5 per cent. chromic acid. 
Pteropods are preserved well in Pereny’s Fluid for fifteen minutes, 
whence they are passed to 50 per cent. alcohol. Gymnosomatous 
forms should be first narcotized with r per cent. chloral hydrate, and 
then killed in acetic acid or sublimate. 
Decapod Cephalopods may be fixed directly in 70 per cent. alcohol, 
making an opening on the ventral surface to allow the alcohol to reach 
the internal parts. 
Bryozoa.—The genera Pedicellina and Zoxosoma may be left for 
an hour in ı per cent, chloral hydrate, and then killed with cold 
corrosive sublimate, washing them immediatety afterwards. Some 
species of Bugula give good results when the expanded animals are 
suddenly killed by pouring over them hot corrosive sublimate. With 
other forms it is sometimes possible to preserve them well expanded by 
adding 7o per cent. alcohol gradually to the surface of the water in 
which they are, or by narcotizing first in weak chloral hydrate or in 
alcoholized sea-water. The results are, however, uncertain, and de- 
pend largely on the skill of the preparator. 
Brachiopoda may be treated in the same manner as Lamellibranchs. 
Tuntcates.— Clavellina, Perophora, and Molgula may be killed with 
the orifices expanded by immersing them in r per cent. chloral 
hydrate for 6 to 12 hours. They should then be killed in chrom-acetic 
mixture, No. 2, and quickly transferred to 1 per cent. chromic acid, 
injecting some of the fluid into the body. After half an hour they 
should be transferred in 35 per cent. alcohol, the injection being re- 
peated, and finally to 7o per cent. Other simple forms may be treated 
in the same manner, or may require the 2 per cent. solution of 
chloral hydrate, or may be killed by pouring a little 1 per cent. 
chromic acid on the surface of the water in which they are, subse- 
quently hardening in 1 per cent. chromic acid. The method recom- 
mended for Perophora may be employed for compound Ascidians, us- 
ing, however, corrosive sublimate instead of the chrom-acetic mixture. 
