Lepeophtheirus dissimulatm^—LEW is 
antennal process the first maxilla and the post- 
oral process the second maxilla. In this latter 
case the first pair of identifiable appendages 
behind the mouth thus become the first maxil- 
lipeds and the last pair of appendages before 
the thoracic legs become the second maxillipeds. 
With the use of the term "maxilla” for the first 
pair of identifiable appendages behind the 
mouth, the term "maxilliped” is here applied to 
the pair of appendages anterior to the first tho- 
racic legs. 
The maxillipeds are first present in the co- 
pepodite ( Fig. 17 i) as uniramous, two-seg- 
mented appendages attached to the ventral sur- 
face of the cephalothorax posterior and slightly 
medial to the base of the maxillae. The first 
segment is slightly less than twice the length of 
the second; its proximal end is broad and has a 
poorly developed articulation surface that pro- 
jects from the middle of the surface. The lateral 
margins of the first segment are slightly curved, 
the anterior margin flatly concave, the posterior 
flatly convex; the distal anterior margin is tap- 
ered sharply, inward to the narrow distal end. 
Both the distal and inner distal lateral surfaces 
have several rather heavily sclerotized projec- 
tions and depressions, each fitting depressions 
or receiving projections from the proximal sur- 
face of the second segment. The second segment 
is slender, the inner margin shorter than the 
outer although both are slightly irregular. The 
distal region of the second segment is tapered 
to the short distal surface which bears a strongly 
developed, spinelike terminal process that curves 
medially evenly. A slender, short, spinelike struc- 
ture is present as an accessory process and arises 
from the inner distal surface of the segment. 
The division between the segment and the ter- 
minal process is distinct and complete, that be- 
tween the segment and accessory process indis- 
tinct and incomplete; the terminal process bears 
a membranous fringe along the inner margin. 
The first chalimus maxilliped (Fig. 17;) is 
more strongly developed than in the copepodite. 
The first segment is approximately the same 
length, with regard to the second segment, al- 
though appearing heavier, its width being 
slightly greater than one-third of its length. The 
inner proximal surface of the first segment pro- 
jects as a tapered articulation process, and the 
lateral margins of the segment are flatly convex, 
227 
the outer margin longer than the inner; the dis- 
tal surface is angled inward and downward and 
possesses two distinct, heavily sclerotized articu- 
lation surfaces for the second segment. The sec- 
ond segment, including the terminal process, is 
tapered from the broad proximal to pointed 
distal end. The proximal region of the segment 
has two lobate projections, one from the ante- 
rior surface and the second from the posterior, 
which articulate with the indentations of the 
distal surface of the first segment. A small seta- 
like accessory process arises from the inner sur- 
face of the segment, at the distinct junction of 
the segment and the terminal process. The ter- 
minal process is heavily sclerotized, curves in- 
ward, and lacks the marginal membrane of the 
previous stage. 
The changes that occur in the maxilliped 
from the first chalimus to the adult (Fig. 17 k-p) 
are relatively minor. The general shape remains 
the same and the armature of the Second seg- 
ment does not change. The articulation surface 
that projects from the proximal region changes 
slightly, becoming somewhat longer in the sec- 
ond chalimus ( Fig. Ilk) and then gradually 
curving in the third chalimus (Fig. 17/) and 
fourth chalimus (Fig. 11 m) until it becomes 
almost recurved in this and the fifth chalimus 
stages. The articulation projection then becomes 
lobate in the sixth chalimus (not visible in Fig. 
17o) and the adult (Fig. Up). The inner sur- 
face becomes grooved in the fifth chalimus and 
remains that way up to and including the adult. 
The division between the second segment and 
terminal process becomes rather indistinct in 
later stages of development. The adult male 
maxilliped has a small shelflike structure that is 
present on the middle of the inner margin of 
the first segment. This structure appears in the 
last moult, from the sixth chalimus to the adult, 
and is the only apparent difference between the 
maxilliped of the female and the male. 
Sternal Furca 
The sternal furca is a single process between 
and slightly posterior to the maxilliped bases 
and is another structure about which little is 
known. Most authors have simply reported its 
presence or absence and utilized this as a tax- 
onomic characteristic. The position of the struc- 
ture, posterior to the maxilliped bases, does not 
