ANDREWS: ANNULUS VENTRALIS. 
439 
the tube over an oblique wall; it is also not a single horizontal space 
as indicated in figures 27 (pi. 47) and 10 (pi. 43) but it extends dorsally 
some distance as two pouches, one right and one left as is indicated 
in the vertical transverse section (pi. 43, fig. 8). This is cut across 
the promontory just where the tube ends above the recess. In the 
middle of the figure is shown the oblique ending of the tube and the 
bridge-like rim above, which, in figure 10 (pi. 43), seems to spring 
across the suture from side to side. Above this rim is the widely 
expanded recess opening, above in the figure, to the surface by a slit 
and, laterally, extending dorsally alongside of the tube termination 
for some distance as a blind pouch. The pouch on one side is larger 
than that on the other side. 
This dorsal pouching of the recess leads to such appearances as 
shown in figure 20 (pi. 45) when the recess and terminal part of the 
tube are full of sperm. This is a horizontal section through the 
promontory and near the ventral surface. The tube is seen sweep¬ 
ing into a median position and blindly ending full of sperm cut off by 
thin lateral walls from the two large sperm masses which fill the 
pouches of the recess. In more ventral sections of this series the lateral 
pouches were continuous with one another and then had a common 
connection with the median tube over the rim shown in figures 8 and 
10 (pi. 43) and 14 (pi. 44). 
As seen in figure 10 (pi. 43) the median suture extends posteriorly 
much beyond the end of the trumpet tube; for a short distance this 
part of the suture connects by a slit with the recess as seen in figure 8 
(pi. 43) and thus the recess could discharge both anteriorly over the 
rim into the end of the slit leading from the tube to the surface (pi. 
44, fig. 14), and ventrally by its own slit direct to the surface. Soon, 
however, the median suture passes posterior to the recess and a very 
long stretch of it extends to the posterior border of the annulus with¬ 
out any connection with internal spaces. In section 16 (pi. 45) which 
is posterior to section 8 (pi. 43) the extreme posterior end of the recess 
is shown full of sperm as seen from the posterior face so that the bridge 
and end of the tube are faintly indicated in the thickness of the section. 
«/ 
The sperm is seen passing somewhat upward toward the external 
suture through a bent imperfect slit. It seems that the slit is here 
only in part a natural slit lined by cuticle and from its bottom goes 
off to one side a mechanical break leading into the sperm mass. Still 
farther posteriorly (pi. 43, fig. 9), the suture has not even this arti- 
