414 MABEL BISHOP 



logical aiul topographical evidence, when checked by comparison 

 with the normal sides of the teratological head, identifies the 

 median isolated ganglion as a conjoined geniculate ganglion, 

 the 'anterior' pair of nerves as great superficial petrosals, the 

 'posterior' pair as infraorbital branches of the Vllth nerve, and 

 the pair that take origin from the under side of the ganglion as 

 median chorda tympani, although, as stated earlier in the paper, 

 no median lingual nerves seem to be present. 



If these interpretations are correct, they establish morpho- 

 logical symmetry of parts for each head, although topographically 

 the organs lying nearest the external surface of each head have 

 been considerably cramped and somewhat reduced in size, and 

 the more dorsal structures have been the most dislodged from 

 their normal position in this mandibulomaxillary complex. The 

 striking fact lies not in these regulatory, topographical adjust- 

 ments, it seems to me, but in the tenacious dominance of the 

 normal morphological relationships. 



Wilder ('08) was right in interpreting the isolated gangHon 

 as a member of the cerebrospinal system, rather than of the 

 sympathetic, but the anatomical evidence identifies it with the 

 seventh nerve, not with the ninth or tenth, as he thought. 



Central connections of the cranial nerves and the associated fiber 



tracts 



In the normal regions of the teratological head. The course of 

 the nerve fibers within the brain is exceedingly difficult to follow 

 because they are non-medullated and are not stained with a 

 specific stain. The following account is therefore more or less 

 fragmentary. 



No special word concerning the olfactory and optic nerves 

 need be added here. 



III. The oculomotor nerves arise in typical manner from 

 ventral neuroblasts of the mantle layer of the mesencephalon. 

 They give rise to fiber strands that converge into rootlets which 

 emerge in a common trunk from the concavity of the cephalic 

 flexure. Neither the nucleus nor decussating fibers were identi- 

 fiable (fig. 8). 



