Andrews. — Annulus Yentralis. 
0 
PLATE 46. 
0 
Fig. 21. Ventral view of a left-handed annulus of Cambarus virilis, cleared in 
clove oil; the shading indicates opacity. 
Fig. 22. Enlargement of some sperms of Cambarus afjinis, from section 
shown in figure 17 (pi. 45). 6X2 mm. 
Fig. 23. Dorsal view of middle part of exoskeleton of a right-handed annulus 
of Cambarus virilis, cleared in clove oil. Tube filled posteriorly 
with sperm and anteriorly with wax. 
Fig. 24. Ventral view of annulus of Cambarus clarkii, cleared in clove oil, 
showing suture as a dark line ventral to tube of trumpet. Ante¬ 
riorly the suture opens as a narrow orifice, somewhat on the right. 
Fig. 25. Ventral view of posterior part of annulus of Cambarus bartoni decal¬ 
cified and cleared in clove oil, showing connection of tube and 
recess. The broken lines indicate inner ends of clefts leading 
from suture which is shown by a heavy line. 2 X A. 
Fig. 26. Ventral view of annulus of Cambarus bartoni, cleared in oil of clove. 
