198 PACIFIC SCIENCE, VoL XVII, April 1963 
TABLE 1 
Armature of Hypothetical Thoracic Leg Shown in Figure 1 
MARGIN 
STERNAL 
PLATE 
PROTOPODITE 
1 2 
EXOPODITE 
1 2 3 
1 
ENDOPODITE 
2 3 
Outer 
f 
lrh 
1H 
2H,lHm,lQ 
c,C 
c,lh 
c,2p',2P 
Inner 
IP 
f,lp,ls 
1H' c,lP 
c,5P 
IF 
c,2P 
2P 
a distinct space is visible between the anterior 
end of the body and the cuticle. There is in- 
distinct evidence of internal segmentation pos- 
teriorly. The general body color in life is light 
yellow with numerous red and blue pigment 
spots scattered over the surface. The eyes are 
visible as two minute, clear, round lenses, one 
on each side of an irregular, reddish-pigmented 
region in the anterior portion of the body. The 
alimentary tract is not visible, neither are the 
mouth nor the anus. Large globules of material, 
presumably yolk, are evident, clustered in an in- 
distinctly delimited, oblong mass extending pos- 
teriorly from just behind the ocular region. 
The first nauplius possesses three sets of ap- 
pendages (described later), the uniramous an- 
tennules, biramous second antennae, and bira- 
mous mandibles in this order proceeding poste- 
riorly. All of these appendages possess long, 
Fig. 5. Greatest width as a per cent of total body 
length, excluding setae, of developmental stages of L. 
dissimulatus. n, Nauplius; co, copepodite; ch, chalimus. 
lightly plumose setae that presumably function 
as flotation mechanisms and in swimming. 
The first naupliar stage lasts for 41/2-13 hr 
with an average of 6 V 2 hr (based on nine hatch- 
ings at room temperature, approximately 23 C). 
After this time the movement of the animal 
decreases slightly and the cuticle splits longi- 
tudinally at the dorsal anterior end. The nau- 
plius then wriggles violently and breaks through 
the split, freeing itself from the cuticle. 
The body of the second nauplius (Fig. 8 d, e) 
is similar to that of the first, although the length 
from the mandibles to the posterior end of the 
body is greater. The greatest length, excluding 
the appendages, is almost 2Vi times the greatest 
width. The body is very slightly flattened dor- 
soventrally in cross section, the anterior end is 
broadly curved, and the lateral margins are flatly 
convex. The posterior end of the body is similar 
to that of the first nauplius although the bal- 
ancers are slightly larger and arise from two 
small, circular, platelike processes in the pos- 
terior lateral indentations (Fig. 16/). 
The bodies of older second nauplii have a 
small space between the anterior end and the 
cuticle. There is distinct evidence of internal 
segmentation, similar to the segmentation of 
the copepodite, visible inside the cuticle of older 
specimens but not visible on the external sur- 
face. The alimentary tract is indistinct and in- 
complete, visible only as a cluster of yolk glob- 
ules along the median longitudinal axis just 
posterior to the ocular region. 
The basic structure of the three sets of ap- 
pendages of the second nauplius is similar to 
that of the first. The armature, however, is 
slightly different. This stage lasts for 91/2-19 
hr with an average of 14V2 hr (based on eight 
hatchings at room temperature, approximately 
23 C). Just prior to moulting into the copep- 
odite stage, the movement of the animal be- 
