58 
PACIFIC SCIENCE, Vol. IX, January, 1955 
TABLE 1 
ARMATURE of the Legs of Alkali gus tripartitus N. SP. 
LEGS 
BORDERS 
STERNAL 
PLATE 
PROTOPODITE 
EXOPODITE 
ENDOPODITE 
I 
II 
I 
II 
III 
I 
II 
III 
I 
outer 
IP 
Ih 
4H 
inner 
IP 
c 
c 
II 
outer 
f 
f, Ih 
f, IH 
IH 
Irh, Ih, IQ 
c 
c 
inner 
IP, Irh 
f, Irh 
c, IP 
c, IP 
5P 
IP 
c, 2P 
6P 
Ill 
outer 
f 
C, Ih 
IH', 2CC 
c 
inner 
IP, f, Irh, CC 
Ip, 2H 
IP 
IV 
outer 
IP 
IH 
3H 
inner 
Abbreviations in the rable: C, row of cirri; CC, area covered with cirri; c, row of hairs; f, membraneous flange; 
H, longer spine; h, shorter spine; H', hook; P, longer plumose spine; p, shorter plumose spine; Q, spine ciliated 
on one side, rimmed with membrane on the other; rh, rudimentary spine. Roman numerals indicate the numerical 
orders of legs, or of joints composing them, and Arabic the numbers of spines or other structure with which they 
are armed. 
tinct areas; grooves bordering areas largely 
obliterated leaving a pair of L-shaped wrinkles 
on posterior region. Fourth thoracic segment 
small, 0.3 as wide as carapace, one-third as 
long as wide, and narrowed anteriorly. Gen- 
ital segment longer than carapace, more than 
a half wider than its own length ; lateral parts 
expanded as a pair of wings, slightly bent 
ventrally, with well-rounded margins. An- 
terior margin with shallow median depression 
to receive the preceding segment, posterior 
margin with insignificant obtuse lobe on 
either side. Abdomen expanded as a flattened, 
cordiform region which is only slightly nar- 
rower than genital one, but longer, and wider 
anteriorly than posteriorly. Its anterior end 
abruptly narrowed for articulation with gen- 
ital segment, posterior end produced as pair 
of blunt lobes with shorter, narrower, quad- 
rate, median lobe between them. 
Frontal plates a pair of small, transversely 
fusiform lobes, separated by a median sinus; 
each lobe with an oval sucking disk on ventral 
face, not covering first antenna. First an- 
tennae with apical joint rodshaped, tipped by 
stiff setae, basal joint more slender than usual, 
but fringed with relatively longer plumose 
spines. Terminal joint of second antennae 
with sharp, slightly curved tip and 2 basal 
spinules, preceding joint about as long as 
terminal, but broader, with rugged posterior 
border, basal joint very short. Mouth tube 
broad, conical. First maxillae absent. Second 
maxillae close to side of base of mouth tube, 
with swollen base and fusiform apex. First 
maxillipeds end in 2 unequal, sharp, winged 
claws and with transverse row of setae a little 
before base of claws. Palm of second max- 
illipeds with strong basal bulge on inner side, 
daw with 2 papillae, one on each side of 
broad base. (Terminal part of the claw was 
unfortunately damaged when the body was 
detached from the host gill in all specimens.) 
Sternal furca wanting. All pairs of legs small 
and feeble. Setae fringing spines of legs rather 
sparser than in ordinary caligids. Armature of 
each pair of legs as indicated in Table 1. 
First legs devoid of any spines on inner 
border of third joint; terminal spines unequal 
in length, with or without fringing hairs. Ru- 
diment of endopodite in the form of relatively 
large, conical lobe. External spine on first two 
exopodite joints of second legs well-devel- 
oped and pectinate on two opposite sides; 
