46 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 
a few sections further forward, thus bringing us to the 
anterior end of the very extensive hermaphrodite repro- 
ductive system (compare Pl. IV. fig. 9). 
The gradual increase of the dorsal area of large ectoderm 
cells, and of the thickened test covering it, is very notice- 
able, and the point where ectoderm and test join and thin 
off into a delicate membrane (xX in PI. II. fig. 5) can be 
seen to advance further and further down the wall of the 
body until in section 155 (Pl. III. fig. 1) it has almost 
reached the ventral surface. We are now approaching the 
anterior end of the stomach. ‘This extensive cavity has 
been gradually changing its shape in the sections from a 
vertical bilobed to a single horizontal space lying across 
the middle of the body (see Pl. III. fig. 1) between the 
dorsal branchial sac and the ventral rectum. In the next 
few sections the walls are found encroaching irregularly 
upon the lumen, and in section 163 (PI. III. fig. 2) the 
lumen has completely disappeared, and a couple of sections 
further forward (PI. III. fig. 8) no trace of the wall of the 
stomach is left. 
Just before we finally leave the stomach behind we come 
upon the posterior end (really the morphological anterior 
part) of the great ventral appendage or * tail?*) (Bie isis 
fig. 1, app.). Consequently the tail jos the body just 
about on a level with the anterior end of the stomach. 
No trace of the tail is visible in section 125 (Pl. II. fig. 5,) 
while it is seen just completely separated off from the 
ventral body-wall in section 155 (Pl. II. fig. 1). It first 
appears a few sections behind this, and it is the lateral 
edges of the tail which first become free, and lastly the 
median part lying between the notochord and the rectum 
separates off from the ventral wall of the body. From this 
point the tail is present in all the sections forward to the 
front or oral end of the body, and even for a considerable 
