222 
to each other or overlap slightly. A slight open- 
ing is visible in the proximal portion through 
which the mandibles project into the cone. Rela- 
tively little change occurs in the mouth cone 
from the copepodite to the adult although be- 
cause of the size and nature of the cone, a com- 
plete analysis was not made. In the adult, how- 
ever, both the hyperstome and hypostome pos- 
sess several heavily sclerotized strengthening re- 
gions on their lateral surfaces. The distal end of 
the cone is membranous, very flexible, and finely 
setuliferous. 
Postantennal Process 
The postantennal process is discussed after the 
mandible because of the possibility that it is a 
true appendage (Heegaard, 1947:59, 203-206). 
The terminology used, with regard to the au- 
thor’s present beliefs, is the same as that used 
in Lewis (in press). The fact that, in L. dis- 
simulatus, this process does not appear until the 
third chalimus, long after all of the other oral 
appendages are present, is an indication that it 
is not a true appendage, although Heegaard 
(1947:205) presents a hypothesis for its late 
appearance. The arguments both for and against 
the term "appendage” being applied are, how- 
ever, strong enough so that this author prefers 
not to commit himself until further studies can 
be made. 
The postantennal process of the third chal- 
imus (Fig. 1 6m) is a blunt-tipped, spinelike 
process projecting posteriorly from an indistinct 
plate on the ventral surface of the cephalothorax 
posterior and lateral to the base of the second 
antenna. The proximal end of the process bears 
two minute nodules, each with one setule. 
The postantennal process of the fourth chal- 
imus (Fig. iGn) is more strongly developed 
and sharply pointed than that of the preceding 
stage. The indistinct plate still bears the process, 
from the base of which arise two minute nodules 
as in the preceding stage, each with a single 
setule. 
The postantennal process of the female and 
male fifth chalimus (Fig. l6o ) is more strongly 
developed than in the preceding stage; the proc- 
ess has become distinctly curved medially and, 
in addition to the two single setule-bearing nod- 
ules on the proximal end, now has a third nod- 
ule just medial to the distal region of the proc- 
PACIFIC SCIENCE, Vol. XVII, April 1963 
ess. The plate from which the process of the 
preceding two stages arose is now almost com- 
pletely invisible. 
The postantennal process of the female and 
male sixth chalimus (Fig. 1 6p) is curved me- 
dially as in the preceding stage. The proximal 
region is, however, more developed, the inner 
margin irregular, not evenly curved as in pre- 
vious stages. Two nodules are present on the 
proximal end but, in contrast to the last three 
stages, each now bears two fine setules. Only 
one setule was visible on the third nodule, al- 
though the extremely small diameter and short 
length of the setules made observation difficult 
and the number may be incorrect. The plate 
from which the process arises is more distinct 
than in the preceding stage. 
The adult female and male postantennal proc- 
ess (Fig. 1 6q) is similar to that of the sixth 
chalimus, although the distal end is more sharply 
curved. The proximal nodule of the two nodules 
on the base of the process now gives rise to 
three setules, the distal nodule to four. The 
third nodule of the chalimus stages did not ap- 
pear to be present. 
Postoral Process 
The postoral process is of the same general 
make-up as the postantennal process, although 
it is first present on the copepodite instead of 
the third chalimus. The process has been called 
the first maxilla and the second maxilla. Its 
structure, in addition to the location of the 
origin of the subesophageal ganglionic nerve 
that innervates it (adjacent to nerves that go 
to the lateral musculature and the postantennal 
process) and the inability to determine its an- 
lage, has caused the author to use the term "post- 
oral process.” 
The postoral process of the copepodite (Fig. 
I6r) consists of a posteriorly projecting, well- 
developed, distally pointed process and two 
setule-like projections just medial to the proxi- 
mal end of the process. Both the process and 
the projections arise just lateral and slightly pos- 
terior to the base of the mouth cone. The inner 
margin of the process is convex, the outer con- 
cave with a slight proximal swelling. A minute, 
heavily sclerotized, lobelike structure is present 
just lateral to the process and appears to be con- 
