60 
PACIFIC SCIENCE, Vol. IX, January, 1955 
basal spine on outer border of third joint 
rudimentary, middle one stouter, apical one 
ciliated on inside, winged on outside. Exo- 
podite of third legs obovate, with two outer, 
finely pectinate spines and inner plumose one; 
apical portion of basal hook elongate, straight, 
and doubly edged with fine pectination. En- 
dopodite small lunular lobe indistinctly sep- 
arated from basal apron. Ventral face of latter 
with short cirri covering small area close to 
boundary with median plate. Fourth legs 3- 
jointed. Apical spines graded in length from 
within outwards, middle one subequal to one 
on penultimate joint, each finely pectinate 
and accompanied at base by transverse row 
of minute spinules. Genital segment with 
short spine on ventral face of each postero- 
lateral lobe. Caudal rami terminal, oblong, 
armed with 3 plumose spines at end, another 
similar, but much shorter, at inner distal angle, 
two at outer angle, and minute cirrus on 
ventral face near anterior end, also with row 
of hairs on inner border. Egg tubes relatively 
broad not extending much beyond abdom- 
inal end. 
male. Similar to other caligid males in gen- 
eral appearance; 1.45 X 0.79 mm., excluding 
caudal rami. Transparent, colorless. 
Carapace half length of body, about as long 
as wide, orbicular, with well-rounded sides, 
and slightly convex above; anterior border 
narrow. Dorsal ribs forming H, dividing cara- 
pace into narrow lateral and broad central 
areas. Longitudinal ribs straight, slightly di- 
vergent forward, reaching nearly to carapace 
margin, each united to margin by short diag- 
onal rib. Transverse rib at posterior three- 
fifths of carapace, only slightly arched forward. 
Eyes close to anterior end of cephalic area. 
Thoracic area broadly rounded on free margin, 
which extends beyond lateral lobes. Sinuses 
undeveloped. Fourth thoracic segment about 
one-fourth as wide as carapace, half as long 
as wide, widest through limb bases, having 
acuminate sides and short, more or less rugose, 
posterior waist. Genital segment two-fifths as 
long as and two-fifths as wide as carapace, 
barrel-shaped, with broadly rounded sides. 
Abdomen slightly longer than preceding seg- 
ment, but narrower, and 2 -segmented; an- 
terior segment short, somewhat wrinkled on 
surface and irregular on sides, posterior seg- 
ment much longer, oblong, with even sides 
and bifurcate end. 
Frontal plates small, but prominent, and 
separated by broad median sinus, each with 
broad membrane and short spinule as well as 
circular disk. Terminal joint of second an- 
tennae short but sharp, prehensile claw, with 
one spine; second joint columnar and folded 
over basal joint which articulates with sternum 
by broad base. Each first maxilla an elongate 
spine, with slightly curved tip. Palm of second 
maxillipeds with large basal bulge on anterior 
face; claw elongate, sharp, well-curved, with 
short spinule on posterior face and papilla on 
other face. Exopodite of third legs with short 
extra spine next outside innermost spine, 
their basal apron without spine on outer mar- 
gin. Genital segment with fifth and sixth leg 
rudiments on ventral surface, fifth somewhat 
behind center of segment on either side as 
papilla tipped by 3 spinules, sixth represented 
by broad, longitudinal ridge at each postero- 
lateral angle with single spinule remaining. 
Otherwise as in female. 
remarks. Alicaligus appears to be more or 
less nearly allied to Caligodes Fleller, Para- 
petalus Steenstrup and Liitken, and Abasia 
Wilson, all of which have the posterior body 
segments either expanded or elongate. It may 
be distinguished from the species already 
known in those genera by one or a combina- 
tion of the following characters: the fourth 
segment is very small in size, the genital seg- 
ment has no processes of any kind, and the 
abdomen is not only elongate, but also ex- 
panded. Although the new genus resembles 
most closely Parapetalus hirsutus (Bassett- 
Smith) in the constitution of those segments, 
it is much different in the mode of life and 
in the structure of the carapace. The present 
species clings to the host gills without moving 
