A nth essius—l L LG 
347 
types occur. The illustration and description of 
the fifth leg in the female corresponds in rough 
essentials to the condition in the paratype, but 
one element of the armature was omitted. For 
the male, the maxilliped was described and 
figured in approximate correspondence with 
that of the paratypes, but Wilson overlooked 
a well-developed basal segment, so that the 
appendage was referred to as 2 -segmented. 
DESCRIPTION: Female (Figs. 12-22): Body 
length 2.0 mm., greatest width 1.40 mm., based 
on Wilson’s original description. Body of rather 
generalized cyclopoid contours, but with meta- 
somal and abdominal segments distinct, so that 
posterior regionalization is not emphatic. Ce- 
phalosome a fused complex bearing appendages 
through first swimming legs and comprising .4 
of total body length, measured from apex of 
cephalosome to end of a caudal ramus. Original 
description stated that segment of the first legs 
is fused with the cephalothorax and indicated 
so as an antomical segment by slight marginal 
indentations. Paratypes (topotypic) from La- 
guna Beach (USNM 54082) showed the seg- 
ment so clearly delimited as almost to justify 
considering it a free element. Paratypes from 
Anaheim Slough, California (USNM 64062) 
show fusion as in the original description. 
Antennule (Fig. 13) essentially 7 -segmented, 
but with complicated articulation and integu- 
mental modification between second and third 
segments, so as to suggest either coalescence or 
incipient separation of an additional minute 
segment, which if present would raise number 
to 8. Approximate proportional lengths of seg- 
ments, basal to distal: Segment I, 3; II, 6.5; 
III, 1.5; IV, 6; V, 3; VI, 1.5; VII, 1. Setae varying 
in length, count per segment undeterminable 
due to poor preservation of available specimens. 
Antenna (Fig. 14) with segmental composi- 
tion much obscured by additional flexures, in- 
volving integumental folds, and torsions of one 
region of appendage on adjoining regions, prob- 
ably essentially 3 -segmented. Basal segment 
without clear-cut, apical articulation, bearing 1 
short external seta. Second segment with very 
complicated distal articulation, this proceeding 
diagonally across appendage; 1 short seta dis- 
tally and externally inserted. Terminal segment 
with cuticularized ridges and folds and with 
very broad distal margin furnishing insertion 
for 4 elaborately articulated clawlike elements 
and 2 setae. Another seta near distal margin. 
A subapical group of 4 setae of diverse lengths. 
Total elements — 4 claws, 7 setae. 
Mandible a flat plate, with cuticularized 
anterior and posterior margins. Appendage 
terminating in long lashlike blade with com- 
plicated marginal ornamentation. Two most 
basal elements of ornamentation flat structures 
compound apically and articulating with margin 
of appendage. Remainder of ornamentation a 
row of graduated denticles. On anterior margin 
of mandible articulated a long lashlike auxiliary 
seta with conspicuous marginal ornamentation. 
Maxillule of characteristic type for genus, an 
elongate lobe with flaring apex. On apex a 
more medial spine and far lateral seta. More 
detailed description presented for male, below. 
Maxilla (Fig. 15) with very long articulation 
with body. Characteristic massive basal segment, 
on which articulating flattened apical segment, 
with heavy cuticularization. Apex produced 
in sharp angle anteriorly, with toothlike ex- 
pansions of cuticle forming medial saw-edge. 
Five large teeth formed by flangelike protru- 
sions of cuticle. Apex produced as more elon- 
gate spinelike process, to total number of out- 
growths 6. In some specimens there may be 1 
more or 1 less tooth. Inserted at base of angle 
of curvature of distal segment, and lying on 
surface, an articulated, fairly long seta. 
Maxilliped (Fig. 16) a prominent mouthpart, 
as seen in general habitus of mouth area, but 
with little development of segmentation or 
ornamentation. Three segments suggested by 
folds and flexures of integument. Terminal por- 
tion with folds and indentations of cuticularized 
surface, but with no elements of armature. 
First legs (Fig. 17) with well-developed 
Figs. 12—26: Anthessius navanacis (Wilson). The scales accompanying certain figures represent 0.1 mm. 
Female: 12, urosome; 13, antennule; 14, antenna; 15, maxilla; 16, maxilliped; 17, first leg; 18, second leg; 
19, third leg; 20, fourth leg; 21, fifth leg; 22, anal segment and caudal ramus. Male: 23, segments of fifth 
and sixth legs; 24, maxillule; 25, maxilliped; 26, fifth leg. 
