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compared with that of the glossopharyngeal and that of the 
branchial branches of the vagus, and the conclusion was drawn, 
that the portio dura is the nerve of the mandibulo-hyoid cleft 
(commonly called the first visceral cleft), and is distributed to 
the (morphologically) anterior and posterior walls of that cleft. 
As a corollary from this conclusion, it followed that the pte- 
rygoid arcade does not represent an independent visceral arch, 
but is a dependence of the mandibular arch, as Gegenbaur has 
already argued upon other grounds. It was further shewn that 
the distribution of the second and third divisions of the fifth nerve 
is such as accords with the view that they represent the posterior 
division of the nerve of the trabeculo-mandibular cleft. The 
anterior division of that nerve was sought in the palato-nasal 
branch of the trigeminal—while the first division of the latter 
nerve appears to be the nerve of the (morphologically) anterior 
face of the trabecula. The sixth, third, and fourth nerves were 
regarded as special branches of the nerves of the mandibulo- 
hyoid, and trabeculo-mandibular clefts respectively, developed 
in relation with the special muscles of the eye. The author 
finally endeavoured to shew that the results thus obtained by 
the thorough investigation and comparison of the distribution of 
the cranial nerves were in entire accordance with those obtained 
by the study of development, and that the apparent anomalies 
in the distribution of the fifth and of the seventh nerves in the 
higher vertebrata are easily explained by the metamorphoses of 
the trabecular and mandibular and hyoidean arches in these 
animals. 
Professor Humpury expressed his thanks and the thanks o 
those present to Prof. Huxley for the careful and lucid account 
which he had given of a difficult piece of anatomy, and for the 
interesting and morphological inferences which he had deduced 
from them, and also for the illustration he had given of the fact 
that the dullest, most troublesome anatomical details may be 
brightened, and so rendered easy by an insight into their true 
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