344 
EDWARD PHELPS ALLIS. 
and rabbit, it is formed from the upper ends of the branchial 
myotomes — five in Scyllium, four in Chrysemys, two in Gallus, 
and three in the rabbit. In view of the facts that in Scyllium 
the subspinalis and interbasales, developed from trunk- 
myotomes, are attached to the pharyngobranchials, and that 
the trapezius is innervated only by the Xlth — the most 
posterior of the vagus roots — even though a constituent from 
the glossopharyngeal (first branchial) segment takes part in 
its formation, it is probable that the absence of levatores 
and associated method of development of the trapezius in 
Scyllium, Sauropsida, and rabbit are secondary phenomena, 
and that the primitive condition is a series of levatores formed 
from the uppermost portions of the branchial myotomes.” 
The trapezius is thus said by Edgeworth to be a muscle that 
is wholly of branchial origin but that varies greatly in the 
branchial myotome or myotomes from which it is derived, and 
in the adult Scyllium, at least, it is definitely stated that the 
muscle is innervated by the eleventh nerve alone. It is also 
elsewhere definitely stated (loc. cit.,p. 281) that muscles 
derived from the trapezius are innervated in Lacerta by 
spinal nerves alone, and in Gallus and the rabbit both by the 
eleventh nerve and by spinal nerves ; and frequent references 
to the trapezius being innervated by the eleventh nerve, or 
by the eleventh spinal, leads one to conclude that Edgeworth 
considered the muscle to be innervated by that nerve, or by 
spinal nerves, in all vertebrates. The muscle is, accordingly, 
one of those to which I made reference in the opening para- 
graph of this paper as being said by Edgeworth to be inner- 
vated by the nerve of a segment of the body other than that 
from which the muscle is developed. The condition of this 
muscle, as found in the adults of fishes, does not, however, 
warrant this conclusion in so far as it applies to them. 
In the adult Heptanchus certain fibres of the trapezius are 
said by Vetter to be inserted on the branchial bar of the 
most posterior, or seventh, branchial arch, the remaining 
fibres of the muscle being inserted on the shoulder-girdle. 
Between the seventh branchial bar and the shoulder-girdle 
