182 
PACIFIC SCIENCE, Vol. IX, April, 1955 
row of five spines; much feebler spinules are 
scattered on anterior face chiefly along mar- 
gin. Plumose spines on the apron biarticulate, 
their distal article hairy all around its circum- 
ference. Caudal rami subterminal, obovate, 
with notched end where they bear three sim- 
ple and one plumose spines, all short. 
Male (Allotype, Figs. 2h-l> 3): Paler than 
female, 9-2 X 5.5 mm. 
Carapace resembling that of female in out- 
line, frontal plates relatively wider, attaining 
3/5 the entire width, and spinules on thoracic 
area smaller in number. Fourth thoracic seg- 
ment 2/7 as wide as carapace, 2/5 as long as 
its own width, trapezoidal, with dorsal plates 
reduced into small, triangular lateral lobes 
ending in sharp spinule; posterior margin 
slightly convex on the median. Genital seg- 
ment oblong, twice as long as wide and half 
as long as carapace. It carries a number of 
spines regularly arranged over dorsal face and 
those crowded along anterior parts of lateral 
borders on ventral face. Abdomen short and 
narrow, two-segmented, about 2/5 as long 
as preceding segment. First segment quadri- 
lateral, with a pair of spines on dorsal side; 
second segment as long as the first, but 
widening backwards and with a round median 
boss at the end. 
Spines on basal joint of first antennae thin- 
ner, more numerous, and covering somewhat 
wider marginal area than in female. Consecu- 
tive joints of second antennae peculiar in 
structure and articulating one with another 
at right angles. First joint has at outer distal 
angle a low triangular bulge with file-like 
surface, and articulates with second joint by 
inner distal angle. Second joint is cylindrical, 
and carries a sharp, proximally projecting 
spine at inner distal angle on posterior side 
and two round bosses with filed surface on 
terminal border, one on anterior and posterior 
sides respectively. Third joint is attenuating 
towards the curved tip, and furnished on 
inner border about the middle with a short 
conical process and along outer border with 
three low bosses, basal one of these being 
tipped by a sharp spine and succeeding one 
bearing, in addition to it, a series of narrow 
folds resembling petals of a flower. Second 
maxillipeds somewhat feebler than in female, 
but similar in structure. 
Exopodite of second legs complicated in 
structure: First joint shorter than correspond- 
ing one of female. Second joint bears at its 
outer distal angle a long, cylindrical process 
which extends alongside with outer margin 
of elongate third joint as far as to its tip. The 
process is thickly covered over its posterior 
face by minute papillae, and carries on the 
outside close to the base a short finger-like 
process and on the inside a long whip-like 
appendix, which reaches the tip of the process 
and ends in a small ciliated knob. Third joint 
is elongate, but narrower than others, and its 
outer border is grooved to receive the named 
appendix of second joint. Outer, triangular 
ridges on basal apron of third legs provided 
with no more than two spines. Fourth legs 
tipped by simple and plumose spine. Caudal 
rami damaged. In other characters as in female. 
Preserved in Mie Prefectural University. 
remarks. A. echinatus, found originally on 
Sphyrna diplana , is a parasite of S. zygaena in 
the present case. As already pointed out by 
Capart, the female of this parasite closely 
resembles that of A. crassus Wilson which 
infests the latter host. It is noteworthy that 
the two parasites on the same host are more 
nearly allied to each other than they are to 
any other species of the genus. They are also 
close to each other in the characters of the 
male. The fourth segment of the male echi- 
natus, however, is not constricted in front to 
form a short neck as in crassus . 
REFERENCES 
Capart, A. 1953. Quelques copepodes para- 
sites de poissons marins de la region de 
Dakar. Inst. Frang. d’Afrique noire , Bui. 15: 
647-671. 
Wilson, C. B. 1932. The copepods of the 
Woods Hole region, Massachusetts. U. S. 
Natl. Mus Bui. 158: 1-635, pis. 1-41. 
