410 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
(d, c. sp.) and the thoraco-abdominal process (th. ab.gpr.) are barbed. The alimentary- 
canal can be traced. At gl is seen the gland cell produced into the frontal horn. 
Fig-. 12 is a more enlarged drawing of the under surface of the body. The large 
“upper lip” bears a row of seta? on each side of its distal portion. At the distal 
end of this row there is a group of seta? about twice as long as the others. Along 
the axis of the lip there is a band 
(muscle? or gland?) which loses itself 
in the horseshoe-shaped dark area 
about the mouth region. The stout 
masticatory blade (masc. hi.) on the 
protopodite of the second appendage 
is to be observed. 
Fig. 13 gives a lateral view of 
the anal region. The alimentary 
canal is very much reduced in its 
most posterior part. The dorso- 
caudal spine arises just dorsal to the 
anus (a) and the thoraco-abdominal 
process immediately ventral. The 
point of insertion of the large muscle 
previously referred to (ms. th. ah.) 
can be seen, and just at that place 
there seems to be an articulation, 
but no observations as to the actual 
place of flexure were made on the 
living nauplius. 
Several methods were tried to raise or obtain older stages of the nauplius, but 
with scant success. It was found that the nauplii of the smooth JB olanus barnacle 
growing on the carapace of the crab could be raised to the cypris stage by keeping 
them in an aquarium jar of water, to which was added every day or two some 
sediment from another jar containing a culture of diatoms, a method suggested by 
Dr. Caswell Grave. The interval between the 
first and second molts and that between the 
second and third molts were, with Balanus. 
one to two days each. This and other aqua- 
rium methods were used with Dichelaspis, but 
only once was a third stage reached. In this 
case the aquarium was started August 22; on 
August 29 the nauplii were found to have 
undergone at least a second molt; they dif- 
fered from the nauplii of the second stage little, except in size, the length having 
increased to 1.13 mm with the other proportions likewise larger. " 
Fig. 13. — Same as fig. 11. Lateral view of posterior 
part of alimentary canal, etc. x 280.' 
* Professor de Filippi states that he failed to get the nauplii of D. darwinii further than the second stage of their 
development, and he argues from this and from other facts (form of the larva, means of locomotion, etc.) that the nauplial 
life is very long (’01, p. 75, and ’61a, p. 205). But it is quite possible that further effort with Grave’s method will show 
that the metamorphosis does not. take an exceptional length of time. 
