PLATE Xa: 
Explanation of Figures. 
Fic. 1. Branchiodrilus menont; anterior end of a specimen 
with four ventral setal bundles in prebranchial region ; no ventral 
setal bundle is to be made out in the segment of the first gill ; the 
first gillhas apparently been damaged; xX 85. 
Fic. 2. Branchiodrilus menont, anterior end of a specimen 
with three venttal setal bundles in prebranchial region ; the second 
gil lhas been damaged; the dorsal vessel is seen on the left side 
of the oesophagus; X I50. 
Fic. 3. Branchiodrilus menont; anterior end of a specimen 
with no ventral setae in prebranchial region ; none could be seen in 
the first gilled segment either; X 85. 
Fic. 4. Branchodrilus menont ; a specimen in which asexual 
division is taking place, and is apparently nearly completed; X68. 
Fic. 5. Branchiodrilus menoni; transverse section of the 
prebranchial region, showing structure of pharynx and position of 
pigment cells. The specimen is that shown in fig. I; X 150. 
Fic. 6. Branchiodrilus menont ; transverse section through 
the sixth gill, showing position of blood-vessels, pigment cells, 
etc. ; same specimen as fig. 4; X 150. 
Alim., alimentary canal; chl., chloragogen cells (much resemb- 
ling pigment cells); c. m., circular muscular layer ; d. v., dorsal 
vessel; ep., surface epithelium; g., gill; 7. v. lateral commissural 
vessel ; /. m., longitudinal muscular layer ; fzg., pigment cells in 
various situations ; pf., pharynx; v. . c., ventral nerve cord (the 
apparently empty space dorsal to it in fig. 6 is the giant fibre) ; 
v. v., ventral vessel. 
All the figures drawn with Zeiss’s Abbe’s drawing apparatus. 
The two sections (figs. 5 and 6) are seen from their front face ; 
hence left and right are reversed. 
