PACIFIC COAST OLIGOCH®TA, 147 
with two parallel grooves in the equatorial region. The posterior somites are very 
wide and four-ringed, but the segmentation is irregular, 
Ovipore a little interior to seta 1; nephropores outside of seta 4. 
INTERIOR CHARACTERS. 
Body-wall. Thereisa special zone of sense organs in the anterior somites as in 
Benhamia, but they are more scattered than in this genus. The longitudinal muscles 
run irregularly, with no trace of bipinnate arrangement. The strands are rather 
narrow. The longitudinal layer is very narrow, especially in the clitellum. The 
transverse layer consists of only 3 to 4 strands. The hypodermis offers nothing of 
special interest. 
The longitudinal layer in the clitellum is greatly diminished in thickness, most 
so in the lateral and dorsal region of the clitellum. Anteriorly in somites ii and iii, 
the longitudinal strands leave the body-wall and spread out fan-shaped to the inner 
wall of the prostomium, forming retractor muscles for the upper and lower lips. 
Arciform muscles. In somites xx, xxi and xxii we find on each side of the 
ventral nerve-chord several oblique or aciform muscles, running from the region of 
the copulatory grooves to the region above the lateral sete, thus serving to depress 
and relax the two grooves. These muscles are confined to a single row, and do not 
show a complex arrangement, as is so frequently shown in oligocheeta. 
Septa. The septa between somites vii and xiv are much thicker than the others, 
especially thickened are those separating somites from vii to x. Those between x and 
xiii are less thick than the anterior ones. The thickest septa, vil/vili, vili/ix, ix/x, are 
much thicker than the body-wall. The most anterior thick septum is the one which 
posteriorly bounds the gizzard (fig. 74). 
The septum next anterior to this, the one which separates the two gizzards, 
presents the peculiarity of not being attached to the body-wall, between yi and 
vii, but it extends forward parallel with the intestine and passes in front of the brain 
on the upper side, while the ventral side is attached to the cesophagus below the 
pharynx. It forms thus a sac, as in various species of Benhamia. Anterior to this 
septum I find no trace of others. 
Alimentary canal. The pharynx is well developed and superposed by a very 
large glandular mass, which consists of about six layers of lobes, attached to muscular 
strands, as usual. The most posterior mass is the thickest. The discha rge pockets of 
these glands into the pharynx are much thicker than any I have seen in other species, 
but are otherwise not of any characteristic construction. 
Septal glands are situated far back in somites vii to xi. They are of the same 
nature as those which discharge in the pharynx, but I have good reasons to believe that 
the glands in this species discharge in the tubular intestine. I have been able to 
follow the discharge duct as far as to the muscular layers of the intestine, which would 
hardly have been the case if the ducts had continued forwards into the pharynx, as 
do those of the forward septal glands in many genera. A peculiarity of these glands 
is that they are especially developed on the ventral side of the intestine (fig. 75) and 
Memoirs, Vou. II, 5. January 6, 1896. 
