424 
PACIFIC SCIENCE, Vol. XIX, October 1965 
mal. The longest tube measures 40 mm and the 
diameter varies from 0.11 to 0.13 mm. One 
striking feature of this species is the length of 
the solid, yellowish rings and the interspaces. 
Most rings measure about 0.05 mm but vary 
from 0.04 to 0.09 mm long, while the clear 
spaces are usually about 0.045 mm. The edges of 
the rings are irregular. The anterior and pos- 
terior regions of the tube are clear and there is 
a short transition area from the ringed to the 
clear region, rather than a gradual fading out 
as in the preceding species. There are several 
species of Siboglinum with rings of a compara- 
ble length, but either the diameter is larger 
(e.g., S. japonicum and S. timorense) or else 
they have paired rings or doublets or are more 
regular in appearance (e.g., 5'. pusillum and 
S', hyperboreum ) . 
The post-annular region is largely missing 
in both specimens but other measurements are 
as follows ( in mm ) : 
MEASUREMENT 
A 
B 
Anterior girdle to tip 
of cephalic lobe 
6.9 
10.8 
Distance between girdles 
0.91 
1.8 
Diameter of trunk at girdle 
0.116 
0.105 
Forepart of body: length 
0.77 
0.69 
Forepart of body : width 
0.105 
0.093 
Ratio of width to length of 
forepart 
1/7 
1/7 
The cephalic lobe is small, rounded, and 
somewhat flattened. The tentacle is 35-45 g in 
diameter and there are two rows of pinnules 
present. The length of the pinnules is about 
equal to the diameter of the tentacle. A post- 
tentacular groove is present and, in addition, 
there are two partial grooves, or wrinkles, far- 
ther back on the mesosome. 
The bridles are colorless and not very dis- 
tinct. They join ventrally but there is a gap on 
the dorsal side about Va the diameter of the 
mesosome. There are no other distinguishable 
features on the pro-mesosome. 
The mesosome-metasome division is cleai 
and there are about 30-35 pairs of metameric 
papillae present, followed by scattered glandu- 
lar patches. There are two girdles which do not 
completely encircle the trunk. They are com- 
posed of a single row of platelets which are 
about 13-14 fx long. The spermatophores are 
long, thin (about 80 g, by 7 /*), and pointed 
at both ends. The filament was not observed. 
? GEN. ET SP. 
Figs. 9-12 
A third species is represented by three 
empty tubes, 15, 18, and 79 mm long. The 
longest tube is divided into three regions: 2 mm 
clear and limp, 16 mm of obvious segmentation 
FIGS. 9-12. Tube of ? gen. et sp. 9, The abrupt transition from the clear 
region to that of narrow rings. 10, Anterior section showing dark area where 
two segments come together. 11, Regular rings in the midportion. 12, Posterior 
region showing the double nature of the rings with irregular openings between 
the members of the doublets. 
