Lepeophthewus dissimulatus— Lewis 
217 
mose terminal seta is borne by this segment. 
The endopodite is two-segmented and attached 
to the ventral lateral surface of the protopodite. 
The division between the endopodite and pro- 
topodite is also indistinct and incomplete. The 
first segment is about 3 times the length of the 
second; its proximal end is narrow and the seg- 
ment is curved slightly to the broader distal end. 
The lateral and distal margins of the second 
segment are continuous and form a broadly 
rounded margin. A strong spinelike projection 
is present on the middle of the distal end of the 
second segment and a slender spinelike projec- 
tion is present on the posterior distal end. The 
second segment also bears two lightly plumose 
setae from its anterior distal surface. 
The second antenna of the second nauplius 
(Fig. 15 b) is similar to that of the first nauplius 
in general outline and make-up. The spinelike 
projections on the third and fourth segments of 
the first nauplius exopodite are absent in the 
second although the remaining armature is the 
same. The make-up and armature of the two 
endopodite segments is the same as that of the 
preceding stage with one exception: the two 
spinelike processes on the distal surface of the 
second segment appear to be more strongly de- 
veloped. 
The second antenna of the copepodite (Fig. 
15 c, d ) is uniramous and three-segmented. The 
appendage is attached to the anterior ventral 
surface just medial to the posterior edge of the 
antennule base. Wilson (1905:542) indicates 
that the caligid second antenna is still biramous 
in the copepodite stage and Heegaard (1947: 
56, fig. 14) describes and figures the reduced 
exopodite on the second antenna of Caligus 
curtus. Unless the small setule (Fig. 15 d) or 
one of the projections on the proximal segment 
of the second antenna of L. dissimulatus is the 
remnant of the now absent ramus of the bira- 
mous second naupliar appendage, no evidence of 
a biramous condition is present. The first seg- 
ment of the copepodite appendage is short and 
irregular, folded in several places, and possess- 
ing two backward-projecting, broadly-angled, 
spinelike processes, the proximal of which is 
poorly developed and the distal well developed. 
The division between the first and second seg- 
ments is distinct although irregular. The second 
segment is broad proximally but tapered to a 
narrow distal end; the lateral margins are regu- 
lar, the distal surface concave. The second seg- 
ment possesses a small lappet-like process pro- 
jecting from the middle of the posterior medial 
surface. The third segment is short, less than 
one-eighth the length of the second; the proxi- 
mal end is slender, the distal is broad, and both 
lateral margins are convex. The distal end of the 
third segment is flat except for a slight depres- 
sion in the middle. A large spinelike terminal 
process curves anteriorly from the posterior one- 
half of the surface; a slender, seta-like accessory 
process projects from the anterior surface. 
The first chalimus second antenna (Fig. 15e) 
appears to have degenerated somewhat; its shape 
is rather indistinct and the entire appendage 
appears flabby. The second antenna of this stage 
is attached just posterior and medial to the an- 
tennule base. The first segment is broad proxi- 
mally, somewhat narrower distally, and the gen- 
eral outline is irregular. The distal end of the 
first segment forms an articulation surface for 
the second segment. The second segment is well 
developed; its greatest length is slightly more 
than the combined lengths of the first and third 
segments. This segment is broader proximally 
than distally, and the lateral margins are irregu- 
lar, the outer longer than the inner; the distal 
surface faces inwards and its margin is generally 
flat. The third segment is short and truncate, 
tipped by a sharply curved, heavily sclerotized, 
spinelike process; the accessory process is pres- 
ent as a small seta-like structure on the distal 
one-half of the inner surface of the segment. 
The second chalimus second antenna (Fig. 
15/) is attached just posterior and medial to the 
base of the antennule. The first segment is broad 
and irregular in outline; its distal surface forms 
an articulation surface for the second segment. 
An indistinct, posteriorly directed, distally 
pointed process is present on the inner surface 
of the segment. The second segment is well de- 
veloped, twice the length of the combined first 
and third segments. This segment is broad proxi- 
mally and tapers to a narrow distal end. The 
outer lateral margins are smoothly convex, the 
inner irregularly concave; the distal surface is 
angled towards the inner proximal end, and the 
distal margin is slightly irregular. The outer 
margin of the third segment is convex and con- 
tinuous with the outer margin of the short, in- 
