ORGANS FOR SPERM-TRANSFER 269 
into the region whence springs the triangle. These muscles are 
seen in the sections of the triangle (figs. 23, 24) as two black dots. 
These sections, with those in figs. 8, 9, show the anatomy of the 
triangle. Fig. 23 is a section along the line 23 of fig. 22. The 
great thickness of the calcified shell is shown by the black mass. 
The membranous parts are shown by the thin black, as to the left 
in fig. 24. The cavity within is blood space traversed by connec- 
tive tissue strands and faced by epidermis against the shell. In 
Fig. 23 Cross section of the triangle on the level 23 of fig. 22. 2. 90mm. A. 
Fig. 24 Cross section of the same about the level 24 of fig. 22. 2. 90 mm. A. 
fig. 23 the triangle and the distal part of the protopodite are cut 
across with the hollow face to the left. The dense shell mass to 
the left above is the guide ridge, (fig. vimr) which somewhat over- 
hangs the cavity of the triangle and bears on its median face some 
setae, (fig. v1), which are connected at the root with the epidermis 
by the long canals of which one is seen to the left (fig. 23) pene- 
trating the shell. Opposite this on the median face of the endo- 
podite there are also a few setae which do not appear in the 
