214 
surface of the body. The first segment is now 
slightly longer than the second and its proximal 
end is almost pedunculate. The lateral margins 
of the segment are irregular although basically 
parallel; the distal end is slightly convex. The 
second segment possesses two long, lightly plu- 
mose setae, as in the first nauplius, but also a 
short, lightly plumose seta from the inner distal 
margin in addition to one short, spinelike proc- 
ess on the outer distal surface. The membrane 
present on the preceding stage is completely ab- 
sent. The copepodite antennule is visible in 
late second naupliar specimens, incompletely 
filling the appendage; the character of the co- 
pepodite appendage is, however, not definable. 
The antennule of the copepodite is attached 
to the ventral lateral surface just lateral to the 
rostrum. The first segment is almost 144 times 
the length of the second; its greatest width is 
approximately one-half the greatest length. The 
proximal anterior lateral margin (the margin 
that faces anteriorly in situ ) of the first segment 
is strongly convex; the remaining lateral mar- 
gin and the posterior lateral margin are some- 
what irregular. The first segment possesses two 
naked setae from the middle of the anterior 
margin and one naked seta from the anterior 
distal "margin. The division between the first and 
second segments is distinct although slightly ir- 
regular. The greatest length of the second seg- 
ment is slightly less than the greatest width, 
the lateral margins are almost parallel, and the 
distal margin is irregular. The second segment 
gives rise to 11 naked setae from its distal sur- 
face. 
The division between the two segments of 
the first chalimus antennule (Fig. 14^) is in- 
distinct; the appendage is attached to the an- 
terior ventral lateral surface just anterior to the 
indistinct, incomplete ventral groove dividing 
the frontal region from the cephalothorax. The 
first segment is slightly more than IV 2 times 
the length of the second, and the proximal re- 
gion is broader than the distal; the rounded 
proximal end is almost included in the posterior 
margin, and the anterior and posterior margins 
are irregularly convex. A single naked seta is 
present on the proximal one-half of the ante- 
rior surface. The second segment is approxi- 
mately twice as long as wide, the posterior and 
interior margins are generally flatly convex, and 
PACIFIC SCIENCE, VoL XVII v April 1963 
the distal end is rounded. A single naked seta is 
present on the middle of the posterior margin, 
as in the adult; eight naked setae are also pres- 
ent on the distal end. 
The first chalimus antennule shows some de- 
generation from the copepodite appendage. This 
condition is evident in most of the appendages 
in the change that occurs from the copepodite 
to the first chalimus. 
The division between the two segments of 
the second chalimus antennule (Fig. I4g?) is dis- 
tinct. The first segment is approximately twice 
the length of the second, comparatively longer 
than in the preceding stage. The proximal end 
of the first segment is broad; the segment is 
tapered irregularly to the narrower distal end. 
The anterior lateral margin is smoothly convex, 
longer than the irregularly concave posterior 
margin; the distal margin is flat. About 10 naked 
setules are present along the anterior lateral 
margin of the first segment. The second segment 
is twice as wide as long, the lateral margins are 
slightly irregular, and the distal margin irregu- 
larly rounded. A single naked seta is present on 
the middle of the posterior margin of the sec- 
ond segment in addition to nine naked setae on 
the distal surface. 
The third chalimus antennule (Fig. 14/ ) is 
attached to a swelling on the posterior lateral 
portion of the tear-shaped frontal region. The 
greatest length of the first segment is about 
twice that of the second; its greatest width is 
two-thirds the length. The proximal end of the 
segment is angled; the anterior margin is thus 
more than twice the length of the posterior; the 
distal end is irregular and has two distinct swell- 
ings. Six lightly plumose setae arise from the 
anterior margin of the first segment and three 
from the distal margin. The second segment is 
slightly constricted at the junction of the first 
segment and curved convexly distally, causing 
the segment to appear club-shaped. The greatest 
width of the second segment is slightly more 
than one-half the length. As in the preceding 
two chalimus stages, a single naked seta is pres- 
ent on the middle of the posterior margin and 
nine naked setae arise from the distal surface. 
The fourth chalimus antennule (Fig. 1 4g) 
is also attached to a swelling on the posterior 
lateral corner of the frontal plates which are 
now oriented more in a horizontal manner than 
