ATRUDO. 193 
Fig. 120.—TRANSVERSE SECTION THROUGH THE LEECH 
(Atrudo medicinalis). (Mainly after BoURNE.). 
Dorsal Sinus. 
Crop cut in 
three places. Dorso- 
Botryoidal ventral Muscle. 
Tissue, 
Circular 
Muscles. 
Muscles. 
Lateral 
Blood-vessel. 
Nephridium. 
Bladder of Lt 
Nephri- Nephridium, 
die, is Lobe of Vas Deferens. ° 
‘estis Lobe o: e , 
Nephridium. “Nheawe _ \Testicular Coelom, 
: Ventral Testis. 
Cord. Si 
inus, 
On the last annulus of each segment, from segment 6 
to 22 inclusive, there open on the ventro-lateral line 
paired nephridiopores. 
On the first five segments one 
Fig. 121.—DorsaL View of the sense-organs on each side 
OF THE ANTERIOR END jg enlarged into an eye; thus 
OF A LEECH. there are five pairs of eyes. In 
Ser Wee “a tary, the median ventral 
egument@ry’ line the unpaired 
male genital aperture is found in 
segment 10 and the female in 
segment 11. The body is flexible 
and is enveloped in a thin cuticle 
secreted by the simple ectoderm. 
The mouth leads into a sucking 
pharynx, the walls of which contain 
unicellular salivary glands and can 
be pulled out by 
radiating muscles. 
A short wsophagus connects it with 
the crop. This is a thin-walled but spacious sac which 
: 14 
The small dots are the sense- 
organs, of which five pairs are Alimentary. 
large and formed into eyes. 
