165 



166 



167 



168 



169 



170 



171 



172 



173 



174 



175 



176 



Figs. 165 to 176 Antero-dorsal views of embryos of Cryptobranchus alleghe- 

 nieiisis in Stage 14, showing especially the segmentation of the neural plate. Cam- 

 era drawings finished under the binocular, from preserved material. X 6. 



The earliest transverse grooves to cross the neural plate are numbered with 

 Roman numerals in the order of appearance; in front of Groove I the transverse 

 grooves are numbered with Arabic numerals consecutively without regard to the 

 order of appearance. Figure 166 is from the embryo photographed for figures 229 

 and 230; figure 176 is from the embryo photographed for figures 231 and 232. 



512 



