Anthessius — Illg 
371 
proportions, segmentation and armature to that 
of female, all elements seeming to correspond 
in the two sexes. Antennae (Fig. 119) also 
like those of female. 
Oral area (Fig. 117) with characteristic as- 
pect, only differing from that of female because 
of great development of dimorphic maxillipeds, 
these appearing as most conspicuous element 
in complex of mouthparts. 
Mandible (Fig. 120) essentially as in female, 
some minute differences in details of ornament, 
possibly as much expression of individual dif- 
ference as of dimorphism. Maxillule (Fig. 121) 
almost exactly as in female. Maxilla (Fig. 122) 
as in female. 
Maxilliped (Fig. 123) highly dimorphic, de- 
veloped as massive, complicated appendage, ap- 
parently 3 -segmented. First segment not as long 
as second, about .75 as long, unornamented, ex- 
cept for distal lateral clump of spinules. Second 
segment somewhat tapered apically, margin me- 
dial in position in normal posture of appendage 
bearing characteristic ornamentation serving to 
act in conjunction with clawlike terminal seg- 
ment in prehensile function. Medial ornamenta- 
tion consisting of dense patches of denticles. 
In addition, near midpoint of medial margin 
a short, stout spine and another spine at same 
level on inner surface of segment. Terminal 
segment forming very complicated region of 
articulation on apex of second segment, pro- 
longed as curving claw, slightly longer than sec- 
ond segment. One long seta, accompanied by 1 
setule, inserted on expanded region of articula- 
tion with segment 2. 
Dimorphism expressed also in first legs, re- 
maining swimming legs very similar to those of 
female. Protopodites and exopodites of first legs 
( Fig. Ill) essentially as in female. Basal seg- 
ments of endopodites as in female, terminal seg- 
ment of each with lateral spine, 1 apical spine, 
1 apical seta, 3 medial setae, the apical spine 
representing a seta of female appendage. Leg 
2 (Fig. 112), leg 3 (Fig. 113), leg 4 (Fig. 
114) in general aspect and ornamentation es- 
sentially similar to those of female. 
Fifth legs (Fig. 115) only resembling those 
of female in general structure and ornamenta- 
tion, but of different outline and proportionately 
much longer. Length equaling about 3 times 
greatest width. Distal spines and seta much more 
widely spaced than in female. Marginal orna- 
mentation of spinules less developed than in 
female. 
Sixth legs (Fig. 124) ventrolateral on genital 
segment, involved in very complicated manner 
with structure of reproductive opening. Most 
obviously representative of appendage a small 
prominence bearing 2 setae (Fig. 125), the 
more medial with well-developed articulating 
base. 
Caudal rami similar in outline and general 
features to those of female, armature (Fig. 116) 
also corresponding, but rami of greater overall 
size and proportionately slightly wider in male. 
Length 1.3 mm. (1. 2-1.4), greatest width .3 
mm. (.295-305), averages from 10 specimens. 
REMARKS: The species is named for John E. 
Fitch. This gigantic copepod is by far the most 
distinctive form in the genus and stands much 
separated from all other species by the elaborate 
development of the body processes and the form 
of most appendages. Perhaps its unique habitus 
deserves greater taxonomic emphasis than spe- 
cific designation, but I cannot see any addi- 
tional information to be provided by the desig- 
nation of a monotypic taxon for this form. Ex- 
cept for absolute size, the antennae and mouth- 
parts are very consistent with those of other 
species. In the other appendages the numerical 
complement of segments and elements of arma- 
ture are entirely the same as for other species, 
but in outlines and dimensions the structure re- 
mains unique. The typical host is a giant pid- 
dock, boring burrows in substantial rock. The 
copepods occur over the general body surface 
of the host and in its burrows, according to the 
collector. The distribution of this host is ap- 
parently a limited one. An indication of broader 
distribution of the copepod exists in the single 
specimen, collected in Oregon, 1959, from 
Zirjaea, a large boring mollusk, closely related 
to Chaceia. 
SUMMARY: Five species of Anthessius are 
described in detail, two of these, A. haivaiiensis 
(Wilson) and A. navanacis (Wilson), being 
redescribed from type material. These occur in 
Hawaii and Southern California, respectively. 
New species described are A. lighti and A. fitchi 
