384 
PACIFIC SCIENCE, VoL V, October, 1951 
tentacular crown has two or three (Fig. 2) 
pairs of radioles with filaments in pinnate ar- 
rangement; there are no stylodes or radiolar 
eyes. The palpi are paired and filamentous 
(Fig. 2). Eyes (Fig. 2) are present in peristo- 
mium and pygidium, or one or both pairs are 
lacking. The thoracic collar is absent, or de- 
veloped to a varying degree. The first segment 
lacks setae; the second segment has noto- 
setae only, all of them slender and distally 
pointed. Segments 3 to 8 (or only 3 to 5) 
have pointed setae in notopodia; they are 
slender and narrowly to broadly limbate. 
Neuropodia have long-handled uncini (Fig. 
3). Abdominal segments have pointed setae 
in neuropodia and long-handled uncini (Fig. 
5) in notopodia, with teeth in pectinate 
arrangement. 
The genotype, F. sahella (Ehrenberg), has 
peristomial and pygidial eyes; a thoracic 
collar is nearly absent; the tentacular crown 
has three pairs of radioles, and the pinnately 
arranged filaments are in double rows. 
Fabricia Ihnnicola new species 
Plate 1, Figs. 1-9 
COLLECTIONS: Many individuals come from 
estuarine, intertidal mud flats of Newport 
Bay and Anaheim Slough, southern Cali- 
fornia. 
The body is threadlike except for the 
spreading tentacular crown; total length is 
5 to 7 mm. or less; width is 14 mm. or less. 
Color in life and preserved is pale translucent 
to white. The body consists of the crown, a 
simple peristomial ring, eight thoracic and 
three abdominal setigerous segments, fol- 
lowed by a triangular pygidium. 
The tentacular crown consists of paired, 
symmetrical halves with semicircular bases. 
Each half has three long radioles, lacking a | 
weblike membrane. Each radiole has 6 or 7 ' 
to 8 or 10 double rows of slender filaments j 
that rise from the inner lateral side of the 
radioles; successive filaments rise from dif- ; 
ferent levels but all extend distally about 
equally far. The total number of filaments for i 
a larger specimen may be 72 to 100. The dis- * 
tal free ends of the radioles are long and 
smooth (Fig. 2). The paired palpi are long, 
slender, and dusky in color, and extend dis- i 
tally as far as, or somewhat beyond, the j 
radiolar tips. The prostomium is bluntly ij 
rounded to conical; it extends forward so as |i 
to be slightly visible beyond the thoracic li 
collar (to be seen when the tentacular crown j 
is removed), or it is less long and fully con- jj 
cealed. 
The thoracic collar is a high, straight mem- 
brane, continuous all around except for a 
dorsal fusion with the upper side of the ' 
prostomium (Fig. 1); it is closely appressed 
to the base of the tentacular crown around 
its lateral and ventral parts and may be over- 
looked as a separate collar membrane except j 
when the tentacular crown is removed. ! 
The first segment, or peristomium, is I 
longer than those following (Fig. 2); it is 
longer in specimens fixed in the tube than 
in those out of it. On its ventral side is a 
quadrangular, dark area, broadest at its 
posterior margin; it marks the position of the 
oral aperture within the collar and is thus 
between prostomium and peristomium. Dark j 
eyespots are present on the peristomium, | 
visible when the collar is pushed aside. ' 
The second or first setigerous segment is 
shorter than the peristomium and shorter to | 
longer than those following. It is plain ex- 
cept for the notosetal fascicle which carries ; 
from five to eight slender, pointed setae. I 
Plate 1. Fabricia limnicola. 1, Anterior end showing base of tentacular crown and first two segments, dorsal 
view, X66; 2, entire animal with expanded tentacular crown, ventral view, X37; 3, thoracic neuropodial hook, 
side view, X1580; 4, distal end of thoracic neuropodial hook, front view, X1580; 5, abdominal notopodial hook, 
side view, X1705; 6, short thoracic notopodial seta, side view, X2350; 7, long thoracic notopodial seta, side 
view, X1620; 8, long thoracic notopodial seta, back view, X1620; 9, cross section of thoracic notoseta from 
widest region, showing core below and expanded region above, X3240. 
