330 ; H. W. NORRIS 
3a. Ramus posttrematicus X. 2 
3b. Ramus pretrematicus X. 2 Nervus branchialis tertius 
3c. Ramus pharyngeus X. 2 
4a. (Ramus posttrematicus X. 3) 
4b. Ramus pretrematicus X. 3 Nervus branchialis quartus 
4c. (Ramus pharyngeus X. 3) 
5a. (Ramus posttrematicus X. 4) 
5b. Ramus pretrematicus X. 4 Nervus branchialis quintus 
5c. (Ramus pharyngeus X. 4) 
6. Ramus auricularis 
7. Rami laterales dorsalis et medius 
8. Truncus intestino-accessorius 
Rami intestinales 
Ramus lateralis ventralis 
Ramus intestinalis recurrens 
Ramulus laryngeus recurrens 
Ramus accessorius (ad musculum trapezium) 
THE FIRST AND SECOND SPINAL NERVES 
The first spinal nerve arises by two ventral roots and is exclu- 
sively motor. It is not certain that the double nature of its 
roots signifies that it is a compound nerve, for the second, third 
and fourth and presumably other spinal nerves have from two to 
four ventral roots or rootlets. It must be noted that the roots 
of the first nerve are more distinct from each other than are those 
of the other nerves. The main trunk of the first spinal nerve 
soon divides into a dorsal and a ventral ramus. The latter runs 
ventrally a short distance, turns sharply anteriorly and then pos- 
teriorly, and, giving off a few small branches to the neighboring 
muscles, passes postero-ventrally in the inscriptio tendinea be- 
tween the first and second segments of the sub-vertebral hypaxial 
musculature until it reaches the dorsal wall of the pharynx. Pass- 
ing posteriorly along the latter it is joined by the ventral ramus of 
the second spinal nerve. According to Driiner the two rami of 
the first spinal nerve emerge from the vertebral canal through 
separate foramina in the first vertebra. The writer finds that 
the main nerve divides while passing through the foramen, but 
there is no cartilaginous bridge between the two rami such as 
Driiner describes. This difference in description, however, may 
be due to the fact that the specimens studied by the writer were 
more immature than those to which Driiner had access. 
