Fig. 
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Fig. 
£9: 
20. 
21. 
22. 
23. 
24. 
25. 
26. 
Dit 
28. 
SEA-FISHERIES LABORATORY. 259 
PuatTe LY. 
Transverse section of the secreting portion of 
the byssus gland. The section is cut trans- 
versely to the long axis of the foot. x 60 
diam. 
Longitudinal section through a single alveolus of . 
the byssus gland. xX 570 diam. 
Vertical section through part of the body-wall 
of the distal limb of the viscero-pedal mass, 
showing a mucous gland cell opening through 
the epidermis on to the surface of the foot. 
Zeiss apo. 1°5 mm., compens. oc. 12. 
An isolated mucous gland from the distal limb 
of the viscero-pedal mass. Zeiss apo. 1°5mm., 
compens. oc. 12. : 
A radial vertical section of the mantle edge. X 
30 diam. 
A section through the internal labial palp, pas- 
sing parallel to the longest border. X 80 diam. 
Vertical section through the muscular body-wall 
of the proximal limb of the viscero-pedal mass. 
x 120 diam. 
PLATE V. 
Part of a section through a branchia, transverse 
to the branchial filaments, and including two 
groups of filaments. Xx 80 diam. 
Transverse section of a single branchial filament. 
Zeiss apo. 1°5 mm., compens. oc. 4. 
Transverse section through two adjacent bran- 
chial filaments, showing the interfilamentar 
junction. xX about 600 diam. 
