Lepeophthewus dissimulatus — Lewis 
225 
the series of tine-like projections of the copep- 
odite process. The arrangement of the terminal 
processes thus appears to be reversing itself 
and, as will be described for later stages, does 
reverse so that the inner process is complex and 
the outer simple. 
The second chalimus maxilla (Fig. 17c) ap- 
pears to have degenerated slightly from that of 
the preceding stage. The shape varies somewhat 
in different specimens and, in general, appears 
to be of a rather plastic nature. The first and 
second segments are of approximately equal 
length, the first appearing more strongly de- 
veloped than the second. The outer proximal 
corner of the first segment is heavily sclerotized 
and appears to function as an articulation sur- 
face. The distal end of the first segment is 
slightly narrower than the proximal, and the 
lateral margins are somewhat irregular; the dis- 
tal region is heavily sclerotized on the inner 
portion although no distinct articulation sur- 
faces are visible. The second segment is nar- 
rower proximally than distally, the segment ap- 
pearing almost club-shaped. The proximal mar- 
gin of the segment is almost included in the 
inner lateral margin, both lateral margins are 
somewhat wavy, and the distal margin is 
rounded. The inner terminal process is relatively 
longer than in the preceding stage, now being 
approximately twice the length of the outer 
process; further, the process is tapered to a sharp 
point and possesses several minute setules on the 
distal end of the outer margin. The inner termi- 
nal process is simple and lobate, almost identical 
to that of the first chalimus. 
The maxilla of the third chalimus (Fig. lid) 
differs somewhat from that of the second chal- 
imus. The first segment is approximately two- 
thirds the length of the second, its proximal end 
projecting as a curved, lobate process that serves 
as an articulation surface. The outer lateral mar- 
gin is broadly convex, the inner flatly convex; 
the greatest width is slightly less than one-half 
of the greatest length and the general shape of 
both of the segments appears to be more distinct 
than in the preceding stage. The distal margin 
of the first segment is irregular and heavily 
sclerotized, the irregularities serving as articu- 
lation surfaces for the proximal end of the sec- 
ond segment. The second segment is slender, 
and the inner and outer margins are generally 
flatly convex. The proximal margin of the sec- 
ond segment is now completely included in the 
inner margin. The proximal surface possesses 
two small knoblike projections with a concave 
surface between them; both of the projections 
and the concave surface articulate with recipro- 
cal processes on the irregular distal end of the 
first segment. The middle of the inner margin 
of the second segment now has a short groove 
extending from the surface inward and proxi- 
mally; this groove corresponds to the position of 
one of the spines present on the adult append- 
age. The distal end of the segment is tapered to 
a medial point and possesses the two terminal 
processes present on preceding maxilla-bearing 
stages. The inner of the two processes now 
curves sharply outward, over the distal end of 
the outer process, and is minutely frilled along 
its outer distal margin. The outer process is 
lobate, approximately two-thirds the length of 
the inner process; the distal margin bears a 
fine membrane. 
The maxilla of the fourth chalimus (Fig. 17 e) 
still bears the somewhat degenerate appearance 
of the third chalimus appendage. Except for the 
distal end, the first segment is similar to that 
of the preceding stage. The outer distal margin 
of the segment is concave; the distal end of the 
inner lateral margin is also concave, forming a 
knoblike projection at the junction of the two 
which is heavily sclerotized. The proximal sur- 
face of the second segment, included in the 
inner lateral surface, is bilobed. The bilobed 
condition of the surface appears to be due to a 
split or division occurring in the small concav- 
ity separating the two heavily sclerotized knobs 
of the previous stage. The separation between 
the two lobes forms an articulation surface for 
the knoblike projection of the inner distal sur- 
face of the first segment and the lobes them- 
selves articulate in the concavities on the distal 
and inner distal lateral surfaces of the first seg- 
ment. The middle of the inner lateral margin of 
the segment is indented in the region of the 
groove of the preceding stage and bears a single 
spinule. The second segment is tapered slightly 
from the indentation to the distal end, which 
is tipped by the two terminal processes. The in- 
ner terminal process is similar to that of the 
preceding stage, the outer process is slightly 
longer, and the fine membrane now extends 
