PLATE 4 
EXPLANATION OF FIGURES 
17, A, B- Acanthias, 6.5 cm. Transverse sections taken, A, at the front pole 
of the hemispheres, B, somewhat before the foramen monroi. 
18 Acanthias, 8 cm. Transverse section through the foremost part of the 
hemispheres. 
19 Acanthias, 8 cm. Transverse section somewhat behind figure 18. Same 
series. 
20 Acanthias, 8 em. Transverse section somewhat behind figure 19. Same 
series. 
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