EDWARD PHELPS ALLIS. 
858 
trolled and confirmed this innervation by the vagus in 
sections that I have of this fish. In sections of a 75 mm. 
specimen of Polypterus senegalus I also find these 
muscles innervated by a branch of the vagus and not by 
spino-occipital nerves. In Polyodon, which is not cited by 
Edgeworth, the pharyngoclaviculares are said by Danfortli 
(1913) to be practically continuous, at their origin from the 
shoulder-girdle, with the coracoarcualis,.and to be innervated, 
as the latter muscle is, by spinal nerves ; and Danfortli adds : 
“ I could trace no branches of the vagus into their upper 
ends.” I however find, in a series of transverse sections of 
a 141 mm. specimen of this fish, a branch of the vagus going 
into the upper ends of these muscles and apparently inner- 
vating them. The large spinal nerve that innervates the 
hypobranchial muscles passes close to the ventral ends of the 
pharyngoclaviculares, but no branch could be found entering 
them. An artery that accompanies the large spinal nerve 
leaves it and enters the pharyngoclaviculares. 
The anatomical evidence regarding these muscles in the 
Teleostomi and Dipneusti is thus, as in the case of the Elas- 
mobranchii, against the view that they have undergone a 
secondary change of innervation, but it is strongly in favour 
of the view that there are, in these several fishes, two totally 
different sets of muscles that have both been called coraco- 
branchiales, one being of spinal or spino-occipital and the 
other of branchial origin. The muscles of spinal or spino- 
occipital origin are found in the Elasmobranchii, while those 
of branchial origin are found in the Teleostomi and Dipneusti. 
In the Teleostomi, with the possible exception of Polypterus 
(Edgeworth), the muscles are derived from the ventral half of 
the primitive constrictor superficialis of the ultimate branchial 
arch, this portion of this constrictor thus being utilised, in 
these fishes, for the secondary purpose of forming this muscle 
just as the dorsal portion of this muscle has been utilised, in 
the Elasmobranchii, for the secondary purpose of forming the 
musculus trapezius. In the Elasmobranchii the muscles are 
quite probably derived either from trunk myotonies or from the 
