142 Wisconsin Academy of Sciences , Arts , and Letters . 
EXPLANATION OF PLATE XII. 
Fig. 12. Slightly diagrammatic, showing lateral view of upper 
and lower lips. D. 3. lg., Labial gland, so., 
sense-organ of upper and so, of lower lip. oes., 
oesophagus, mt., masticatory teeth of mandible, 
at., atrium, m, Zenker’s “rechenformige Ifauor- 
gan.” ing., infran-oesophageal ganglion connected 
by a, nerve, In., to sense organ of lower 1 lip, so. 
Fig. 12. Lower lip. D. 3., showing the chitinous supports. 
Fig. 13. Zenker’s “rechenformige Kaunorgane.” 
Fig. 14. Part of wall of intestine. 1-12 Im. 3. 
Figs. 15 and 16. Part, of wall of stomach. 1-12 Im. 3. 
Fig. 17. Shell gland. A., anterior. D. 3 
Fig. 17. Slightly enlarged view of bottom) cell to show open¬ 
ing. 
Fig. 18. Unicellular adhesive gland showing gland cell with 
its nucleus^ 1ST., and part of the secretion just below 
it. D. 2. 
Fig. 19. Section through shell duplicature at anterior part of 
body. 0., outer, and I., inner wall. S. Gr., shell- 
gland. Hyp., hypodermal cells. S. Hyp., large 
sub-hypodermal cells. 
Fig. 20. Male reproductive organs. L>., dorsal. A., anterior. 
S. V., seminal vesicle. V., vas deferens. 
