340 The Alligator and Its Allies 
8b and 8c. Two sagittal sections of an embryo of this stage. 
X 43. 
Ficures 8d-8j. A series of transverse sections of the embryo repre- 
sented in Figures 8 and 8a. X 43. 
ga-gm. A series of transverse sections of an embryo somewhat 
more advanced in development than the one represented 
in the last series. X 43. 
Ficures 10 and 10a. Dorsal and ventral views respectively of an 
embryo with eight pairs of mesoblastic somites. X 20. 
(Drawn chiefly by transmitted light.) 
FiGuRE 11. Dorsal view of an embryo with fourteen pairs of meso- 
blastic somites. The area pellucida and the developing 
vascular area are shown, the latter having a mottled 
appearance. The pushing of the head under the blasto- 
derm is also shown. X 20. (Drawn chiefly by trans- 
mitted light.) 
Ficures I1a-11k. A series of transverse sections of an embryo of this 
stage. X 43. 
FicureE 12. Dorsal view of an embryo with about seventeen pairs of 
mesoblastic somites. Part of the area pellucida is 
represented. (Both transmitted and reflected light 
were used in making the drawing.) XX 13. 
FiGuRES 12a-12g. A series of transverse sections of an embryo of this 
stage. XX 43. 
Ficure 13. Surface view of an embryo with about twenty pairs of 
mesoblastic somites. >< (about)15. (Drawn with both 
reflected and transmitted light.) 
Ficures 13a-13f. A series of transverse sections of an embryo slightly 
more developed than the one shown in Figure 13. 
X 20. 
FIGURE 13g. A sagittal section of an embryo of about the age of the 
one represented in Figure 13. XX 20. 
14. Head of an embryo with one pair of gill clefts; ventro- 
lateral view. X 13. 
15. Profile view of the head of an embryo with three pairs of 
gill clefts. XX 13. 
FicurES 15a-15e. A series of transverse sections of an embryo of 
about the age of the one represented in Figure 15. X 20. 
Ficure 15f. A horizontal section through the anterior region of an 
embryo of the age of that shown in Figure 15. X 20. 
16. Surface view in profile of an embryo with four pairs of gill 
clefts. > (about) 12. 
