EXPLANATION OF PLATES. 
The sections are all drawn, unless otherwise stated, by means of the camera 
lucida. 
PLATE I. 
C. L. Herrick. 
Transverse sections of the right hemisphere of Arctomys to a uniform scale. 
Fig. I. Cross-section of olfactory bulb. Cf. Fig. 9. 
Fig. 2. Cross-section of hemisphere and crus olfactorius. 
Fig. 3. Cross-section of hemisphere at the junction of the crus olfactorius. 
Figs. 4-8. Sections taken at frequent intervals across the hemisphere, ex- 
tending as far caudad as the corpus callosum. 
Fig. 9. . Enlarged section of the lobus olfactorius. Compare also Plate II, 
Figs. 1-4. 
Fig. 10. Portion of Fig. 9, enlarged. 
Fig. II. Frontal cross-section of the right hemisphere and corpora quad- 
rigemia of the rat, for comparison with sections figured on Plate V. 
Fig. 12. Cells from cortex of crus olfactorius at point indicated by Fig. 
4, (.025 mm. long.) 
Fig. 13. Small area from cortex of ventral surface of hemisphere, in sec- 
tions passing through the front of the callosum. (C. Fig. 8,) x 170. 
Fig. I4. Portion of cortex from ventral aspect of hemisphere, near median 
portion of the pyriform lobe at the level of the anterior commissure. (Fig. 8 a, 
Plate II.) 
PLATE 11. 
C. L. Herrick. 
Fig. I. Longitudinal vertical section of anterior portion of hendsphere of 
Rabbit. 
Fig. \a. Portion of glomervdar layer of olfactory nerve bundle. 
Fig. 2. Portion of upper cellular layer of crus olfactorius. 
Fig. 3. Section through the granular, ganglionic, and gelatinous layers of 
olfactory lobe. 
Fig. 4. Horizontal section of anterior part of cerebrum, with olfactory 
lobe, Arctomys. 
