Anthessim — -Illg 
363 
as greatest width and 1.2 times as long as anal 
segment. Margins with conspicuous cuHular 
development. Armature 6 setae. Of apical quartet 
of setae, medial of central 2 longest, about 6.3 
times as long as ramus, adjacent seta 3-5 times 
length of ramus. Medial apical seta about 1.6 
times as long as ramus; lateral apical seta about 
.8 times as long as ramus. Lateral marginal seta 
short, about .7 times as long as ramus, inserted 
on lateral margin about at distal .6. ’ Dorsal 
medial seta short, about as long as width of 
ramus, inserted just subapically. 
MALE (Figs. 76-91 ) : Body length 1.25 mm., 
greatest width .56 mm., averages from 10 speci- 
mens. Body (Fig. 80) very similar to that of 
female in size and aspect, but approaching a 
little more closely to generalized cyclopoid type. 
Cephalosome bearing first legs, segment of these 
indicated by very slight marginal indentations. 
Metasome of free segments of legs 2 to 4. XJro- 
some of segments of legs 5, 6, and 4 abdominal 
segments, including element bearing anus and 
caudal rami. Segments of legs 5 and 6 much 
coalesced to form a genital complex, through 
which extend elongate spermatophores. Orna- 
mentation of anal segment (Fig. 81 ) much as 
in female. 
Antennule (Fig. 82) similar in proportions, 
segmentation and armature to that of female, no 
particular dimorphism expressed. 
Antennae and mouthparts, except maxilliped 
as in female. Antenna (Fig. 83); oral area (Fig. 
84); mandible (Fig. 85); maxillule (Fig. 86); 
maxilla ( Fig. 87 ) . 
Maxilliped (Fig. 88) highly dimorphic, de- 
veloped as massive, complicated appendage, 
probably trimerous. First segment about as 
long as second, with row of fine spinules on dis- 
tal margin. Second segment somewhat tapered 
apically, margin medial in position of normal 
posture of appendage bearing characteristic or- 
namentation serving to act in conjunction with 
clawlike terminal segment in prehensile func- 
tion, this consisting of patches of long denticles. 
In addition, near midpoint of medial margin 2 
short, stout spines. Terminal segment forming 
very complicated region of articulation on apex 
of second segment, prolonged as curving claw, 
longer than second segment. One seta inserted 
on expanded region of articulation with seg- 
ment 2. 
Dimorphism also expressed particularly in 
first and third legs, remaining swimming legs 
very similar to those of female. Protopodites and 
exopodites of first legs essentially as in female. 
Basal segments of endopodites as in female, ter- 
minal segment of each with lateral spine, 1 
apical spine, 1 apical seta, 3 medial setae, very 
long apical spine representing a seta of female 
appendage (Fig. 76). Leg 2 (Fig. 77) in gen- 
eral aspect and ornamentation essentially similar 
to that of female. Leg 3 (Fig. 78) showing 
slight dimorphism in that most proximal lateral 
spine of terminal segment of endopodite has 
characteristic shape, a basal knob, angled posture, 
and lacks outlining hyaline flange of other spines 
of rami. Leg 4 (Fig. 78) as in female. 
Fifth leg (Fig. 89) very similar to that of 
female in general structure. Length about 3 times 
greatest width. Accessory ornamentation of spin- 
ules more highly developed than in female. 
Sixth legs (Fig. 90) ventrolateral on genital 
segment, involved in very complicated manner 
with structure of reproductive opening. Most 
obviously representative of appendage a small 
prominence bearing 2 unequal setae, the more 
medial with a well-developed articulating base. 
Caudal rami (Fig. 91) very similar to those 
of female. 
REMARKS: This form is named for John R. 
Norton. The species occurs very commonly in 
association with its typical host in Washington 
Sound, Puget Sound, and also on the outer rocky 
ocean coast of Washington, in the Cape Flattery 
Region, The usual infestation consists of fair 
numbers of the copepod, ranging to several 
dozen. They wander freely in the rather capa- 
cious respiratory cavity of the host, sometimes 
emerging from the dorsal aperture or moving 
over the foot and other fleshy parts. They are 
FIGS. 80 — 91 : Anthessim nortoni, new species. The scales accompanying certain figures represent 0.1 mm. 
Male: 80 , habit, dorsal; 81 , anal segment; 82 , antennule; 83 , antenna; 84 , oral area; 85 , mandible; 86 , max- 
illule; 87 , maxilla; 88 , maxilliped; 89, fifth leg; 90, sixth leg; 91 , part of anal segment and caudal ramus. 
Legend: L, labrum; M, mandible; U, maxillule; X, maxilla. 
