OF THE SKULL IN THE COMMON SNAKE. 
417 
PLATE 31. 
Fig. 1. Fifth stage, 4^ to 5 inches long. A horizontal section of the skull showing 
the floor, from above. X 10 diameters. 
Fig. 2. The same stage and size, showing skull with palatal bones, from below. 
X 10 diameters. 
Fig. 3. Sixth stage. Longitudinally vertical section of skull of ripe Embryo, Gf inches 
long. X 10 diameters. 
Fig. 4. Hinderpart of same skull, seen from the outside. X 10 diameters. 
Fig. 5. Part of same view. X 20 diameters. 
Fig. G. Same skull, hind part, seen from above. X 10 diameters. 
Fig. 7. Mandible and columella of same; inner view. X 10 diameters. 
Fig. 8. Another view of columella. X 20 diameters. 
PLATE 32. 
Fig. 1. Last stage. Adult Snake, upper view of skull and arches. X 5 diameters. 
Fig. 2. The same from below. x 5 diameters. 
Fig. 3. Nasal sacs and vomerine bones, from below. X 5 diameters. 
PLATE 33. 
Fig. 1. Separated cranium of same seen in section.* X 5 diameters. 
Fig. 2. Side view of same. X 5 diameters. 
Fig. 3. Transverse section of same, orbital region. X 5 diameters. 
Fig. 4. Another section, ethmoidal region. X 5 diameters. 
Figs. 5 to 14. A series of transversely vertical sections through nasal region of same, 
from the nostrils to the orbits. X 12 diameters. 
Fig. 15. Vomerine bones and cartilages of left side, outer view. X 5 diameters, 
f ig. 1G. Those of right side, inner view. X 5 diameters. 
* The round space seen on op., in this figure, is accidental. 
3 II 2 
