Lepeophtheims dissimulatus — Lewis 
229 
occur in the time that a structure appears in 
development. If this were possible, then the 
status of the postantennal process must also be 
reviewed. The presence of a short but distinct 
muscle that is attached to the sternal furca and 
the mobility of the process exhibited by adult 
specimens make it difficult to accept Heegaard’s 
suggestion (1947:77-78) that the sternal furca 
is a cuticular spine. 
The sternal furca of the fourth chalimus is 
visible developing underneath the third chal- 
imus cuticle (Fig. 18*). The process is indis- 
tinctly visible between and slightly posterior to 
the bases of the maxillipeds but does not pro- 
ject from the ventral surface. The proximal end 
is broadly rounded, the bifurcation extends less 
than one-half of the total length of the process, 
and the tines are sharply pointed. 
After the moult into the fourth chalimus, the 
sternal furca (Fig. 18 b) is distinct, projecting 
from the ventral surface of the cephalothorax. 
The greatest width of the process is approxi- 
mately two-thirds of the greatest length. The 
bifurcation extends slightly more than two- 
thirds of the length of the process. The tines are 
angled outward slightly and are bluntly rounded 
distally. 
The sternal furca of the fifth chalimus (Fig. 
18c) is well developed. The bifurcation of the 
process extends about one-half the length of the 
process. The tines appear distinct, separated 
from the base of the process by a groove; they 
are also angled outwards slightly and are bluntly 
pointed. 
The tines of the sternal furca of the sixth 
chalimus do not appear distinct from the base as 
in the preceding stage. The bifurcation extends 
slightly more than one-half the length of the 
process; the tines are angled outward slightly 
and are bluntly pointed. 
The sternal furca of the adult male and fe- 
male (Fig. 18e) is more heavily developed than 
in the preceding stages. The tines have a flat 
inner surface in contrast to the round inner sur- 
face of the previous stages but are still angled 
outwards slightly and have a blunt tip. 
Thoracic Leg 1 
The armature and character of the mem- 
branes, spines, and setae comprising the arma- 
ture, are given in Table 2. 
The first thoracic leg is present in the copep- 
odite. The appendage (Fig. 18/) is biramous; 
the protopodite, exopodite, and endopodite are 
each one-segmented. The protopodite is wider 
distally than proximally, its greatest width 
slightly more than the greatest length; a single 
lightly plumose seta is present just lateral to the 
base of the exopodite and an indistinct, seta-like 
process is present on the proximal inner margin. 
The exopodite is palm-shaped, its lateral and 
distal margins continuous. The outer margin of 
the exopodite segment bears four spines, the 
proximal three of which are simple, the fourth 
with a membrane along the outer margin. The 
endopodite is also palm-shaped, the lateral and 
distal margins again continuous. The outer distal 
surface bears a small, triangular, spinelike pro- 
jection in addition to the setae shown in Table 2. 
The distinct shape of the copepodite first tho- 
racic leg is lost in the moult from the copepodite 
into the first chalimus. The first thoracic leg of 
the first chalimus (Fig. 18g) appears flabby, 
the armature seems to have degenerated, and 
the long plumose setae borne by the exopodite 
and endopodite of the copepodite first leg, and 
presumably used in swimming, are lost and re- 
placed by short, lightly plumose setae. The pro- 
topodite is one-segmented, its width and length 
about equal; the distal end is somewhat nar- 
rower than the proximal although this is vari- 
able in different specimens. A single lightly 
plumose seta is present on the distal lateral sur- 
face just lateral to the base of the exopodite, 
and the seta-like process of the preceding stage 
is absent. The exopodite is one-segmented and 
dactyliform, the proximal end is wider distally 
than proximally, and the greatest length is ap- 
proximately 2 l /z times the greatest width. The 
lateral margins of the segment are slightly ir- 
regular, the distal margin broadly curved. A 
lightly plumose seta is present on the middle of 
the outer lateral surface and six lightly plumose 
setae are present on the distal end. The spines 
present on the exopodite segment of the copep- 
odite appendage are completely absent in the 
first chalimus. The endopodite is one-segmented 
and irregularly lobate, its length slightly less 
than two-thirds that of the exopodite. The en- 
dopodite bears two lightly plumose setae on 
its distal surface. 
Two distinct trends can be noticed in the 
