4 MORGAN. [Vor. IX. 
The larvae lived well in small aquaria, remaining at the 
bottom most of the time. No attempt was made to keep the 
young larvae for any length of time, inasmuch as an unbroken 
series of forms could be obtained by surface collecting where 
the conditions had been normal. The larvae that were caught 
and were in a condition to change immediately into the young 
Balanoglossus, could be kept successfully in aquaria. If they 
were sufficiently advanced, they went immediately into the 
sand supplied to them in watch crystals; if not yet ready, they 
developed farther at the bottom of the dish and later buried 
themselves in the sand. The larvae underwent the transfor- 
mation with only a small percentage of abnormal forms, and no 
difficulty was experienced in keeping them for several weeks. 
The water in the aquaria was changed twice a day, and fresh 
sand was supplied occasionally. At a later stage in develop- 
ment they took into their digestive tracts large fragments of 
the coral sand, completely filling and distending the walls of 
the tube. 
An attempt was made to feed the young Balanoglossus 
living in the sand on carmine to determine, if possible, the 
region where excretion was taking place. The coral sand was 
mixed up with finely powdered carmine so that each grain 
was partly covered with particles of carmine. The worms 
would enter this sand, but often came out again and wandered 
around the dish. A few remained for several days, and two 
or three for more than a week. They were then killed and 
afterwards examined by means of serial sections stained with 
picric acid. There was no evidence that the young worms 
absorbed any of the carmine, and the experiment gave entirely 
negative results. It was noticed, nevertheless, that the young 
worms that remained in the sand protruded in a most con- 
spicuous way the walls of the collar-pores, so that each stuck 
out horn-like from the posterior edge of the collar. 
Attempts made to fertilize the eggs were not successful. 
This was partly owing to the difficulty I had at first in getting 
sufficient numbers of the adult worms. An observation was 
made that will prove, I think, of the greatest practical advan- 
tage to any one who may have the opportunity to make a new 
