Lep eophthewus dissimulatus - — Lewis 
231 
The second thoracic leg is first present in the 
copepodite stage. As with the first thoracic leg, 
the appendage appears to degenerate in the first 
few chalimus stages and then gradually takes on 
the appearance of the adult appendage in the 
late chalimus. 
The second thoracic leg of the copepodite 
(Fig. 19 'a), as in all of the remaining stages, is 
biramous. The protopodite is one-segmented, 
the width of the proximal and distal ends being 
about equal and the greatest length about three- 
fourths of the width. The lateral margins of the 
segment are broadly convex, and the distal mar- 
gin is irregular. A single lightly plumose seta 
is present on the protopodite just lateral to the 
exopodite base. The exopodite is one-segmented 
and ovoid, and the distal margin is distinct from 
the outer lateral margin but is continuous with 
the inner. The proximal end of the exopodite is 
minutely bilobed and heavily sclerotized, form- 
ing an articulation surface that is contiguous 
with irregularities on the lateral distal surface 
of the protopodite. The outer surface of the ex- 
opodite bears three spines, the proximal two 
of which are simple, the distal long and fringed 
by a membrane along its outer margin. The 
endopodite is one-segmented, the proximal end 
narrow and the distal end broad; the distal two- 
thirds of the segment is bent inwards. The lat- 
eral and distal margins of the segment are both 
distinct. Both the exopodite and endopodite 
bear several plumose setae as indicated in Ta- 
ble 3. 
The second thoracic leg of the first chalimus 
(Fig. 19 b) is much more simple than the copep- 
odite appendage. The protopodite is one-seg- 
mented, and its greatest length is approximately 
two-thirds of its greatest width. Both of the lat- 
eral margins are continuous with the distal mar- 
gin although the entire outline of the segment 
is somewhat irregular. The single seta present 
on the copepodite protopodite is absent in this 
stage. The exopodite and endopodite are of ap- 
proximately equal length and both are dactyli- 
form. The exopodite is approximately one-half 
as wide as long although slightly wider distally 
than proximally; the lateral margins are wavy, 
the distal broadly rounded. A single naked seta 
is present on the middle of the outer lateral sur- 
face and five lightly plumose setae on the distal 
surface. The endopodite is irregularly rounded 
distally; the lateral and distal margins are con- 
TABLE 3 
Armature of Second Thoracic Legs of Developmental Stages* 
STERNAL 
PROTOPODITE 
EXOPODITE 
ENDOPODITE 
STAGE 
MARGIN 
PLATE 
1 
2 
1 
2 
3 
1 
2 
3 
Copepodite 
outer 
IP 
2h,lHm 
inner 
3P,1Q 
6P 
Chalimus I 
outer 
lp',3P 
2P 
inner 
2P 
2P 
Chalimus II 
outer 
2P,2P 
2P 
inner 
4P 
1P,3P 
Chalimus III 
outer 
lp 
filH 
4H,3P 
c 
c,2P 
inner 
IP 
fils 
c 
c,2P 
IP 
4P 
Chalimus IV 
outer 
f 
lp 
filH 
3H,1Q,2P 
2P,2P 
inner 
IP 
fils 
C,1P 
c,3P 
IP 
3P 
Chalimus V 
outer 
f 
lp 
filH 
3H,1Q,2P 
c,C 
c,lP,3P 
inner 
IP 
fils 
C,1P 
c,3P 
IP 
c,3P,2P 
Chalimus VI 
outer 
f 
Is 
IP 
filH 
1H 
2H,1Q,3P 
c,C 
c 
c,3P 
inner 
IP 
fils 
C,1P 
c,lP 
c,2P 
IP 
c,2P 
3P 
Adult 
outer 
f 
filp 
filH 
1H 
2H,1Q,2P 
c,C 
c 
c,3P 
inner 
Is, IP 
fils 
C,1P 
C,1P 
c,3P 
IP 
c,2P 
c,3P 
* For explanation of symbols see Fig. 1. 
