438 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
posteriorly and anteriorly and any connection between it and the 
recess is not apparent. The cavity of the trumpet, represented as 
empty, seems to end bluntly just anterior to the sperm mass in the 
recess, though it also seems to run under the sperm mass. In the 
original preparation scattered specks indicated the curved slit leading 
from the middle line of the suture dorsally into the long curve of the 
trumpet on the extreme left. 
Only when the sperm is absent and the suture cracked open by 
pressure or by drying does the true relation of suture, recess, and 
trumpet cavity become evident as in figure 10 (pi. 43). In this figure 
the curved surfaces passing from the suture to the cavity of the trumpet 
are represented by parallel rulings. Anteriorly the open suture is con¬ 
nected by a slit or curved passage with the parallel cavity above and 
to the left of it. The walls of the trumpet cavity are represented by 
a double line. This trumpet cavity then passes to the right across 
the suture and above it and curving posteriorly on the right side of 
the suture seems to end in part on the median plane just above the 
suture and in part as a blind in-pushing of the anterior wall of the 
heart-shaped recess. Thus the cavity of the trumpet lies far to the 
left of the suture in the anterior part of this figure and connects with 
it by a long plane or slit, then in crossing the suture, opens directly down 
into it for a short distance and afterwards goes some distance to the 
right of the suture and connects with it by a long curved opening or 
slit. At the posterior end the cavity, coming to the median plane 
again, opens directly down through the suture and it is here very near 
the ventral surface of the annulus. Dorsal to its opening into the 
suture, the cavity runs on posteriorly for a short distance above the 
recess as a blind sac; or one might say the cavity of the trumpet in 
passing ventrally toward the surface runs posteriorly farther than 
necessary and then turns anteriorly again to end just above the median 
suture. The part of the suture posterior to the tube of the trumpet 
is shallow and it would seem as if the heart-shaped recess were entirely 
cut off from the cavity of the trumpet by the transverse wall shown in 
figure 10 (pi. 43) crossing the suture. This, however, is not the case 
since this w T all is some distance dorsal to the mouth of the suture as 
seen in figure 14 (pi. 44) where this wall shows as a nearly horizontal 
shelf jutting out between the sperm in the recess and the sperm in the 
terminal part of the trumpet tube. 
The recess thus has a slight connection with the terminal part of 
