Pogonophora — CUTLER 
423 
FIGS. 1—6. Different regions of the tube of S. albatrossianum from anterior to posterior. 1, Clear, limp 
region. 2, Thin, pale rings appearing. 3 and 4, Lengthening rings in midportion. 5 and 6, Approaching the 
posterior end, where the rings become more irregular. 
The width of the mesosome is 0.09-0.12 mm; 
the ratio of width to length being 1/12-1/14. 
The cephalic lobe is small, rounded, appears 
quite glandular, and lacks a pretentacular 
groove. Just behind the base of the tentacle 
there is a groove on the ventral side only. The 
tentacle measures 35-45 g in diameter and 
bears two rows of pinnules. The length of the 
pinnules varies but usually exceeds the diame- 
ter of the tentacle. 
In unstained material the bridles are very 
difficult to distinguish. After staining with 
hematoxylin they can be seen as very thin lines 
which join ventrally but leave a small gap on 
the dorsal side. There are short, delicate, trans- 
verse lines crossing the bridles, as in S. tenue 
(Ivanov, 1963:240). There are no visible 
glands behind the bridle. The bridle is in the 
middle of the promesosome. 
The metameric glands of the metasome are 
present but very poorly defined. There are two 
girdles which are from 0.55 to 0.63 mm apart 
and each consists of one row of platelets (un- 
cini). The platelets are 11-15 /x long with two 
characteristic groupings of small teeth. In the 
posterior region there are a few scattered papil- 
lae. The spermatophores are more or less 
spindle-shaped and measure about 70 g by 7 g. 
I was unable to distinguish their filament. 
This species is similar to S. weberi, but dif- 
ferent in the following aspects: forepart pro- 
portionally a little longer, bridle about half 
way along the forepart, two rows of pinnules, 
much larger spermatophores, girdles closer to- 
gether, and more double tube rings. It differs 
from S. veleronis in that the bridle is farther 
back on the mesosome, the glandular papillae 
are less well developed, it lacks the cylindrical 
pores on the sides of the mesosome, and the 
toothed platelets are of a different type. 
Siboglinum ecuadoricum sp. nov. 
Figs. 7, 8, 13F 
HOLOTYPE: USNM 31822; PARATYPE: USNM 
31823 
DESCRIPTION: This species is represented by 
two unsegmented tubes, each containing an ani- 
FlGS. 7-8. Tube of S. ecuadoricum. 7, Middle re- 
gion. 8, Portion of the tube containing the anterior 
part of the animal and part of the tentacle. 
