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PACIFIC SCIENCE, Vol. XVII, April 1963 
developed spines, the proximal two extending 
distally and laterally, the distalmost extending 
laterally and curving distally. The simple fourth 
spine of the third chalimus bore a membrane 
on the inner margin and a row of setules on the 
outer in the fourth chalimus; this condition is 
reversed in the fifth chalimus. The endopodite 
is two-segmented; the first segment is short, its 
width slightly greater than the length which is 
approximately one-half that of the second seg- 
ment. Both of the lateral margins of the first 
segment are convex, the outer twice the length 
of the inner. The second segment is irregularly 
palm -shaped, and the lateral margins are irregu- 
lar although distinct from the distal margin; 
the greatest width of the segment is approxi- 
mately two-thirds of the greatest length. 
The second thoracic leg of the sixth chalimus 
(Fig. 19g) is basically the same as that of the 
adult. The protopodite is two-segmented; the 
first segment is short, less than one-third of the 
length of the second. The second segment is 
broader distally than proximally, its greatest 
width approximately two-thirds of the length. 
The lateral margins of the second segment are 
slightly wavy, the inner generally convex. The 
exopodite is now three-segmented, the division 
occurring in the second segment of the previous 
stage, just distal to the proximalmost spine. The 
first exopodite segment is slightly longer than 
the combined lengths of the succeeding two 
segments, and its lateral margins are flatly con- 
vex. The single spine is slightly denticulated 
and strongly developed and extends past the 
distal end of the second segment. The second 
segment is short, flared from the narrow proxi- 
mal to broad, concave distal surface. A single 
simple, although well-developed, spine is pres- 
ent on the outer distal surface. The third seg- 
ment is short, its length approximately equal to 
that of the second segment. The distal one-half 
of the segment is broadly rounded and a small, 
steplike indentation is present in the proximal 
one-half of the outer margin. A well-developed, 
simple, distally projecting spine is present in 
the indentation and a second well-developed, 
simple spine projects laterally and curves dis- 
tally from the outer lateral surface at the junc- 
tion of the curved and indented margins. The 
endopodite is also three-segmented. The first 
segment is approximately equal in length to the 
second; the outer margin is broadly rounded and 
approximately 4 times the length of the short, 
irregular inner margin. The second segment is 
flared from the narrow proximal to broad distal 
end, as in the second segment of the exopodite. 
The outer margin of the second segment is flatly 
convex, the inner slightly concave. The third 
segment is short, being approximately three- 
fourths of the length of the second segment. 
The distal and lateral surfaces are irregularly 
rounded, the margins continuous. 
With the exception of some minor changes 
in the shape and armature of the segments, the 
description of the second thoracic leg of the 
sixth chalimus can be applied to the adult ap- 
pendage (Fig. 19^). 
Thoracic Leg III 
The armature and character of the mem- 
branes, spines, and setae comprising the arma- 
ture are given in Table 4. 
The biramous third thoracic leg is first pres- 
ent as a recognizable appendage in the first chal- 
imus (Fig. 20 a). As mentioned earlier, how- 
ever, two spinelike processes are present on the 
third pedigerous segment of the copepodite and 
may represent the third legs in this stage of de- 
velopment. The protopodite of the third tho- 
racic leg of the first chalimus is one-segmented, 
its greatest width and length about equal. The 
somewhat irregular outer lateral margin is more 
than twice the length of the inner and two naked 
setules are present on the outer lateral surface 
just lateral to the exopodite base. The exopodite 
is one-segmented, broader than long; its lateral 
margins are generally convex and the distal 
margin is flat although variable in shape in dif- 
ferent specimens. Four spinule-like processes 
project from the distal region of the exopodite. 
The endopodite is also one-segmented and 
broadly rounded, both of the lateral and the dis- 
tal margins being continuous; the greatest width 
of the segment is slightly more than the length. 
The protopodite of the third thoracic leg of 
the second chalimus (Fig. 20 b) is much larger 
than that of the preceding stage, most of the 
increase in size being due to the increase in the 
lateral surface. The irregular proximal end of 
the one-segmented protopodite is broad, ap- 
proximately twice the width of the distal end. 
The outer lateral margin is almost 4 times the 
