52 Journal of Comparative Neurology. 



ial cleft. After giving off the cutaneous branch the ramus en- 

 ters m. hyobranchialis to which it gives a motor branch, then, 

 emerging from the muscle, it passes dorsad of the hypo-hyal 

 cartilage and enters the tongue, near its cephalad border. Oc- 

 casionally the r. lingualis merely lies on the ventral surface of 

 m. hyo-branchialis, only the motor branch penetrating the mus- 

 cle. Thus the ramus generally called lingualis is a mixed 

 nerve. 



Nervus vagus. As my study of the vagus is not yet as 

 complete as it is possible to make it even by gross dissection, I 

 shall not attempt a description of all its rami. 



The most cephalic branch gives fibres to the skin cephalad 

 of the branchial cleft and anastomoses with the branch of the 

 glossopharyngeus which innervates the same region. There is 

 also a small motor branch running cephalad to m. constrictor 

 arcuum branchialium, and to the caudal part of m. genio-cerat- 

 oideus. Another slender branch passes to m. levator arcuum 

 branchialium and to the skin caudad of the branchial cleft. 



The largest ramus includes the ramus visceralis and a large 

 recurrent branch. This latter branch is the one figured by 

 Fischer as the hypoglossal nerve, and he was probably at least 

 partially correct, as this nerve receives an anastomosing branch 

 not only from the first but also from the second and third spi- 

 nal nerves. The greater part of the fibres of this nerve are, 

 however, plainly derived from the vagus, and probably repre- 

 sent a ramus rccurrens vagi. It gives branches to m. constrictor 

 pharyngeus, m. depressor arcus branchialis posterioris and m. dor- 

 so-laryngeus, then runs cephalad and appears to end in m. genio- 

 hyoideus. A branch to m. sterno-hyoideus is also derived 

 from some part of this vago-hypoglossal complex. The most 

 caudal ramus of the vagus is a lateral line branch. 



The first spinal nerve has no dorsal root, its origin is almost 

 at the level of the foramen magnum, and it takes its exit by a 

 foramen in the first vertebra. It gives several small branches 

 to the m. longissimus dorsi of the neck region, but the largest 

 ramus is that which anastomoses with the ramus recurrens of the 

 vagus. There are also anastomosing branches which unite this 



