28 
with tig. 20, and fig. 21 with fig. 22); this fact is easily explained by 
the sinuous character noticed on surface views. Independent of this 
variation between the two ridges of any given transverse section, there 
is a marked difference in the transverse outline of the gland in different 
parts of the body. This outline is to some extent correlated with the 
transverse outline of the lateral bands, for, in general, when the bands 
are low radiall}" the gland is likely to be large, while when the gland 
is small the bands are likely to be larger radially. The gland may be 
followed into the posterior portion of the bod}", where it becomes very 
small; toward the esophageal portion of the body, it becomes larger 
and more prominent. 
Another point visible on transverse section is the presence of a dis- 
tinct canal in about the center (axial line) of each gland; although some 
sections were found in which this canal was not distinguishable, it was 
distinct in so man}- sections that its existence can hardly be questioned. 
Fig. 21. 
Fig. 22. 
In some sections, the gland appeared granular, in others it was more 
distinctly reticulate in appearance. 
Surface views of the middle (equatorial) esophageal region (fig. 15) 
show that the two longitudinal glandular ridges dip ventrallv and unite 
to form a bridge; the united structure can then be traced cephalad 
nearly or quite to the excretor}" pore; one canal also is seen to dip 
ventrally and can be traced to the excretory pore; the natural expec- 
tation is that the two canals (one from each side) unite before reaching 
the pore; on surface views the point of union was not recognized. 
On sections the excretory pore w"as confirmed; almost directly dorsally 
of it were at least two (possibh^ several) cells, each with a distinct 
nucleus; tracing the excretory canal caudad it is seen to possess for a 
short distance a rather thick cuticle; suddenly the wall becomes thin 
and the canal seems to broaden into a larger cavity resembling a bladder, 
(fig. 16); several of the following sections are unsatisfactory, but the 
canal can be traced on the nonnucleated side (see below) of the bridge 
