360 
EDWARD PHKLPS ALLIS. 
affiliation with the branchial myotomes, the coracobranchiales 
would have been innervated by a spino-occipital instead of by 
a branchial nerve ; and this is possibly what has occurred in 
the Selachii. 
An adductor arcus branchialis is said by Vetter to be 
found, in all the Selachii examined by him, in each of the 
fully developed branchial arches, which would seem to 
exclude the ultimate arch in each of these fishes, that arch 
certainly not being fully developed. In Chimaera, Vetter 
says that similar muscles are found in the first three 
branchial arches, but that the corresponding muscles in the 
fourth and fifth arches resemble the arcuales dorsales of the 
Selachii rather than the adductores of those fishes. Tiesing 
(1895) says that in Mustelus and the Batoidei there is an 
adductor muscle in each arch, and I find an adductor in each 
of the six arches of the one specimen of Chlamydoselachus 
that I have examined for this purpose. Fiirbringer (1903, 
p. 397) did not find an adductor in the first branchial arch of 
his specimen of Chlamydoselachus. Vetter says that the 
adductores in the Selachii, and also in Chimaera, are all 
innervated by branches of the nervus vagus of the related 
arch, but he does not give the course of those branches. 
Tiesing gives the same innervation in the Selachii and 
Batoidei examined by him, and he adds that the branch of the 
vagus that innervates the muscle perforates, in each case, 
the related epibranchial in order to reach the muscle. In 
Chlamydoselachus 1 also find the nerve perforating the 
related epibranchial, near its anterior edge. The muscle, in 
all the Plagiostomi, and in the first three branchial arches of 
Chimaera, arises from the internal surface of the epibranchial 
of its arch and is inserted on the opposing, internal surface 
of the ceratobranchial of the arch. 
In the Teleostei, Vetter (1878) found no adductores arcuum 
branchialium excepting in one large specimen of Esox, in 
which specimen they are said to be represented by a few 
scattered muscle fibres lying in connective tissue in the angle 
