180 ANNULATA. 
Fig. 106.—TRANSVERSE SECTION OF PoLyGoKDIUS, SEMI- 
DIAGRAMMATIC. (After FRAIVON’.) 
Dorsal Blood-vessel. 
Intestine. 
Oblique Septum 
bearing the 
Gonad. 
Nerve-cord. Ventral Blood-vessel. 
a ring round the cesophagus and a ventral nerve-cord, swollen into 
ganglia in each segment. Immediately behind the prostomium and 
placed laterally are a pair of ciliated pits which are probably sensory. 
Fig. 107.—CORONAL LONGITUDINAL SECTION OF 
PoLtycorpius (Highly Magnified). 
Intestine. 
Circular Blood- 
___vesse! 
Y Nephridium. 
Segment. Nephridiopore. 
Segment. 
The sexes are separate and the testes and ovaries arise on two diagonal 
muscular bands intersecting the ccelom. 
