Anthessius — Illg 
345 
external hyaline flange and internal margin 
entire. Trimerous endopodite with slight flexure. 
Armature: first segment, 1 medial seta; second 
segment, 2 medial setae; third segment, 2 lateral 
spines set in steplike emarginations, 2 apical 
spines, 1 medial seta. Medial setae of all seg- 
ments reduced somewhat in length. Each of 
basal 2 segments produced slightly at distal 
lateral corner as small spinous cuticular process. 
Most proximal spine of terminal segment sub- 
tended by such process, and another apical on 
segment. Each segment with dense row of cilia 
on lateral margin. Spines of terminal segment 
with hyaline flanges. Setae of coxopodite and 
rami with plumose ciliation. 
Fifth legs ( Fig. 11) with probably 2 seg- 
ments represented, basal consisting only of ex- 
pansion on body posteriorly and laterally to 
furnish articulation of distal segment, and with 
a small seta laterally, representing armature. 
Second segment broad, flattened with cuticular - 
ized medial and lateral margins. Length about 
2.5 times greatest width. Armature 2 spines 
and 2 setae, spaced on lateral and terminal mar- 
gins: 1 lateral seta at about distal .8 of lateral 
margin; 1 spine at lateral distal corner; 1 seta 
near medial distal corner; 1 apical spine at 
medial distal corner. Spines subtended by small 
groups of spinules, these continuing as short 
row on distal fifth of medial margin. 
Caudal ramus about 2.5 times as long as 
greatest width and 1.15 times as long as anal 
segment. Setal armature not determinable from 
available material. 
REMARKS: Due to the small amount of type 
material the male of this species could not be 
reinvestigated. According to the original descrip 
tion by Wilson the length of the male is 2.85 
mm., the width 1.25 mm., and the usual fea- 
tures of anatomical dimorphism appear to occur. 
Attempts have been made to re-collect this 
species. The host, as indicated by the original 
description, quite possibly is a fairly common 
form in Hawaiian waters, but no further records 
of the copepod have come to light. 
The species is differentiated from others of 
the genus in the key above. Many details of 
the anatomy should be reinvestigated when well- 
preserved specimens become available. The 
species is one of the larger ones known for 
the genus. 
Anthessius navanacis (Wilson) 
Figs. 12-26 
Pseudomolgus navanacis, C. B. Wilson, 1935. 
Type locality, Laguna Beach, California, 
Navanax inermis (Cooper), type host. 
specimens examined: Wilson’s types were 
seen in the U. S. National Museum, and were 
found to compare reasonably well with the habit 
figures he presented ( but see below, under body 
form). Two female paratypes and two male 
paratypes, one pair each from USNM 54082 
and USNM 64062, were dissected to compare 
with the original description. The specimens 
showed some variation in body segmentation 
and in the strength of development of the spines 
of the swimming legs, but these were of minor 
grade. The specimens in some details in which 
they agree with each other do not correspond 
to some details of the original description and 
accompanying illustrations. Accordingly, the 
species is redescribed below, with details added 
for purposes of comparison with other species 
treated in the present study. Wilson was using 
a different terminology for mouthparts from that 
now current, so his statements about the first 
maxilla refer to our mandible. His description 
and figure for this appendage are in good agree- 
ment with generalities about Anthessius species, 
and, as I was unable to dissect out in good condi- 
tion the mandible from the paratypes I exam- 
ined, I can add no further information. Some 
important discrepancies in the descriptions and 
illustrations for other appendages in the original 
description should be noted. The armature 
described for the second antenna, 6 or 7 stout 
claws and 1 or 2 setae, does not correspond with 
the 4 claws and 7 setae described below. For 
the 4 pairs of swimming legs, a misinterpreta- 
tion of the cuticular specializations of some 
segments led to presentation in the original 
description of an armature which does not cor- 
respond with any known for a species of An- 
thessius. The exopodites are adequately described 
and illustrated. For the endopodites, spinous 
processes were counted as spines and some other 
discrepancies from the condition in the para- 
