576 EMBRYOLOGY 
OF THE TURTLE. 
Part III. 
4a, w-e. 3, ¢, w-c. 4, c) is much larger and longer. The olfactory bulb (fig. 4, 
4a, 10, w-e. 3, d, w-e. 4, d, w-c. 10, a, a’) is distinctly striated by broad bands of 
Wood-cut 3. 
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arr Beat mttinal (arog Lave | chor tear Ae Te ce ibm : 
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Wood-cut 4. 

spheres and of the corpora quadrigemina. The crura cerebri 
(fig. 8, 9, w-e. 8, a”) are already quite prominent. The 
corpora striata (fig. 8, 9, w-c. 8, a, w-c. 9 a) project con- 
white and gray matter; and 
it is more enlarged, and en- 
_-¥ croaches still more upon the 
“-, rather diminished hemispheres, 
(fig. 4, 4a, 8, w-e. 3, ¢, w-e. 4, 
~~or e, w-c. 8, a) than before. The 
cavity of the latter is nearly 
ae w filled by the choroid plexus 
(fig. 4a, 8, w-c. 4, e, w-c. 8, d); 
and the optic lobes (fig. 4, 4a, 
8, 9, w-c. 3, h, w-c. 8, f, f’) are 
again on a little higher level 
than the fourth ventricle, (w-c. 3, ¢) and advanced 
so as to underlie the greater part of the hemi- 
spheres (fig. 4, 4a, 8, w-c. 3, e w-c. 4, ¢, w-e. 8, a). 
The optic nerve (fig. 4, 4a, w-c. 3, 2’) is as yet 
very short, passing almost immediately from the 
optic lobe into the eye. 
The pineal gland (fig. 4, 
4a, we. 38, f, we. 4, f) is a solid mass, sunk 
considerably below the upper surface of the hemi- 
Wood-cut 5. 
Wood-cut 6. 
a 

siderably into the cavity of the 
hemispheres. The corpora quad- 
rigemina (fig. 4, 4a, 7, w-c. 3, 9, 
g, w-e. 4, g, w-e. 7, a, a’) have 
much thicker walls, and are 
more sunk posteriorly toward 
the fourth ventricle. The cere- 
bellum (fig. 4, 4a, 6, wee. 3, 4, 
w-c. 6, a, a’, a’) is very much 
enlarged; it has a much thicker 
wall, and trends almost perpen- 
dicularly to the axis of the 
brain, upward from its anterior 
border (w-ce. 6, a’). The arach- 

