455 
its ramus cutaneus dorsalis is related to the myoseptum 
between the 3rd and 4th myotomes (i. e. the 3rd and 4th post-otic 
somites). The relation of its ganglion to this myoseptum had been 
previously noted by Scorr (’87) and SkipLey (’87). The ventral root 
of the 4th post-otic myotome forms the anterior of the roots of the 
so-called hypoglossus (XII) of Petromyzon. In the later stages of 
development of Squalus, also, the ganglion of the 4th post-otic myotome 
becomes united with the vagus '). 
In the early stages of development the dorsal ganglia of the 2nd 
and 3rd post-otic somites are united in the vagus ganglion, as has 
been previously stated by Scorr (’87). The evidence given by SHrpLey 
(87) as to the relation of the dorsal ganglia to the anterior post-otic 
myotomes confirms the opinion that there are two dorsal ganglia 
united in that of the vagus. He states (p. 361) that “the ganglion on 
the ninth nerve lies in front of the first myomere, between that and 
the ear, whilst that of the vagus lies between the first and second. 
The first dorsal root of the spinal nerves with its ganglion lies between 
the third and fourth myomere.” HATSCHER is clearly incorrect in 
ascribing only one myotome to the vagus”). The rami cutanei 
dorsales of the vagus are represented in the ramus recurrens 
facialis (FURBRINGER), which is definitely related to no myoseptum. 
The ramus cutaneus dorsalis glossopharyngei is likewise 
related to no myoseptum, since it is primarily anterior to the first 
permanent (post-otic) myotome. In late stages of development, when the 
first post-otic myotome has extended forward anterior and lateral to 
the otic capsule in the form of two muscle strands, a dorsal and a 
ventral, the ramus cutaneus dorsalis of the IX. nerve lies in 
1) This union of the ganglia of spinal and cranial nerves is, did we 
accept the view that there is a generic difference between spinal and 
cranial nerves, indeed a most unholy wedlock! 
2) Harscuex (92) states that the “spinalartiger Vagusanhang”, which 
is in Ammocoetes at first an independent nerve, “bei den Gnathostomata 
wahrscheinlich mit dem Vagus verschmilzt”. This is indeed the case, if 
the above stated homology be correct, but this would be the third dorsal 
ganglion which fuses in the dorsal ganglion of the vagus and not the 
second as Hatscnex states. In the later stages of both Petromy- 
zon (?) and Squalus embryos the vagus represents three 
dorsal roots and not two as has been held by van WisHeE (’89) and 
Hatscuexk (’92). It appears to me that this “spinalartiger Vagusanhang” 
is the first dorsal root of the hypoglossus (XII) of WırnERSHEIMm (’80) 
which Antsorn ('84) regarded as the hindmost (8th) root of the vagus. 
Both were right, and the question raised may be regarded as one concerning 
a distinction without a difference. 
