310 MYXICOLA. 
99 
in the “ hepatic” region. In Myzxicola the “ pennate 
great complexity. 
The circulation is similar to that in the Sabellids with certain peculiarities. In the 
abdominal region the sinus surrounds the gut, and from the ventral vessel a trunk passes 
outward to the lateral longitudinal trunk, from which again a branch proceeds upward to 
join, after a dorsal curvature, the intestinal smus. Moreover in the mid-abdomen a dorsal 
dilatation is present at each side simulating two dorsal trunks, but this disappears anteriorly 
and posteriorly. The dilatation occurs where the branch from the lateral vessel joins the 
sinus. A coat of chloragogen covers various vessels both in this species and in Sporographis. 
Moreover in Myzxicola the intestinal sinus has numerous nucleated bridles throughout its 
cavity, and Claparéde thought that its wall had an inner lining of epithelium. 
In the stomachal region the sinus branches out into a great vascular plexus, and, as the 
canal curves downward, the plexus joims a large ovoid vascular reservoir above the 
cesophagus and immediately behind the cephalic ganglia. The ramifications also supply 
what Claparéde calls the duct of the tubiparous gland. In front it forms a large arc from 
which the branchial trunks arise. 
Claparéde (1873) states that a special nerve in Myxicola infundibulum arises from the 
cerebral ganglion, and describing an arc passes to the side of the body and abuts on a 
little fossa between the branchial apparatus and the anterior border of the thorax; such 
is evidently a sense organ. A similar organ exists in Leptochone, Amphiglena and Oria. 
The pair of (segmental) tubes in front secrete the material for the tube. He observed no 
nerves in the cesophagus of Myzxicola infundibulum, nor did he find them in Spirographis 
Spallanzant or Branchiomma vesiculosum or other sedentary annelid. In the annelids the 
branchial artery and vein are united with each other (except in the Spionids) by a system 
of branches. This is antagonistic to the view of De Quatrefages, who held (though he 
afterwards retracted it) that each branchia had a single vessel in communication with a 
series of contractile ampulle in the tissues. 
The nervous system in M. infundibulum shows a tubular fibre with a dilated end in each 
cerebral ganglion and the two tubes pass backward on the dorsum of the connectives to 
the thoracic region, but they unite in the abdominal region to form a single large tubular 
fibre. It is interesting that the cords are double m front, but one gradually diminishes 
and disappears after the union of the tubular fibres to form the large one at the upper 
region of the nerve-cord. 
In Myxicola Cosmovici (1880) is of opinion that the organ of Bojanus consists of a pair 
of pouches which separately debouch into the buccal funnel, and they are distinguished 
by their dark pigment. The segmental organs, on the other hand, occupy each segment 
from the middle of the body backward toward the tail, and have the form of ciliated 
funnels on the posterior faces of the diaphragms opening by a tube which has an aperture 
below the setigerous process of the foot. This differs from the observations of other authors. 
The ova in this form are green (as is the blood), the males being readily distinguished by 
their pallor. 
arrangement of the muscles shows 
Cunningham! (1888) corrects Claparéde’s view that in Myzicola only a single nerve-cord 
exists, and he states that the neural tubes in each cesophageal commissure become continuous 
1 “Quart. Journ. Micr. Sc.,’ n.s., vol. xxvii, p. 272. 
