27 
I no means excluded that this canal-like appearance was an artifact; in 
, fact, certain sections strongdy indicated that it was. In still other sec- 
tions, the middle cell was rather short, but a process from the large 
' gland could be followed centrifugally between the dorsal and ventral 
I halves of the band, nearly or quite to the middle cell. 
j 
i 
100 /U_ 
Fig. 18 . 
The determination of the existing conditions must be left for stud}?' 
of fresh material, notwithstanding a strong indication on some surface 
views of the existence of a longitudinal canal with a lumen of about 
4 to G in diameter. 
Excretory system. — The excretoiy system is very striking, but 
only a part of it can be interpreted at present. 
On surface views of worms cleared in glycerine a large, longitudinal 
ridge, of somewhat sinuous outline longitudinally, is seen on each side 
of the body, in close relation to the lateral bands. On transverse sec- 
tions several prominent characters of this ridge are distinctly visible. 
In the lirst place it is seen that in any given section the transverse 
outline of the two ridges may be entirely different (compare fig. 19 
