484 



L. S. STONE 



absence of the ceratohyal cartilage. The ophthalmic ganglion 

 is large and normal in size, although it is situated somewhat 

 dorsal to its normal position (fig. 85). The portion of the 

 lateral-line ganglion of VII which supplies the supra-orbital and 

 infra-orbital group of sense organs also appears in this level and 

 is normal in size as well as the rest of the lateral-line ganglion. 



g'-^g- 



.-ophpl 



-ecr 



82 



'llg \ 



Fig. 82 Frontal section, showing the ophthalmic placode two days after the 

 crest cells have been removed. X 37. 



Fig. 83 Showing in the same specimen the posterior portion of VII lateral- 

 line placode giving off placodal cells. At its anterior extremity is shown the 

 contact of the gasserian ganglion with the ectoderm. X 37. 



Fig. 84 Showing a normal VII lateral-line ganglion when crest cells have been 

 removed from the hyoid arch. X 37. 



Fig. 85 Frontal section, showing a large ophthalmic ganglion after crest 

 cells had been removed at an early stage. X 37. 



Fig. 86 Frontal section further ventrally in the same individual, showing the 

 palatinus VII at the point of leaving the ganglion. X 37. 



