1880. | Development of Amphioxus Lanceolatus. 9 
that the day time is to these animals a period of rest, when they 
remain entirely buried beneath the surface, and night time a 
period of activity, when they come up to feed and perhaps to 
move from place to place,as they have been seen swimming 
about during the night in the aquarium at the Zoological Station 
at Naples, and on one or two occasions I have found, early in the 
morning, one of my specimens lying entirely out of the sand, 
fully exposed to view, and in all probability it had been: swim- 
ming about during the night. 
On account of the propensity of these animals to remain con- 
cealed from sight it was necessary, whenever they were wanted 
for examination, to drive them from the sand, and this was by no 
means an easy task, as they are such exceedingly active little 
beasts that they would work their way from side to side of the 
dish beneath the sand, very nearly as quickly as I could runa 
stick or pencil through it in trying to find their position. And 
when once forced out, they would dart through the water so 
impetuously, and plunge into the sand again so quickly that 
their movement seemed merely a flash in the water, and a few 
particles of floating sand and mud would alone indicate that one 
of them had been out of their proper domain. Generally this 
chasing process had to be repeated four or five times, when they 
would become exhausted, and after undulating about the jar very 
slowly for a moment or so, they would sink upon the sand and 
remain perfectly quiet, flat upon their sides, for sometimes half a 
day atatime. During these intervals they could be transferred 
from dish to dish and even placed under a low power of the micro- 
scope for examination. But if not completely exhausted a short 
rest would revive them, and then, when touched, they would dash 
away as impetuously as ever, and I have had them, on such 
occasions, rush out of the water and over the broad rim of a 
large plate on to the table, and before they could be touched, — 
much less secured, throw themselves off the table and down upon 
the floor. But the adults appear to be so vigorous that these 
falls, which occurred on two different occasions, did not seem to 
have the least injurious effect. As may be surmised from this, 
all their movements are exceedingly quick, and this rapidity in- 
going through sand and water, and hence the ease with which 
they can move about from place to place, is probably the reason 
why we secured only three of these animals at Fort Wool. 
