676 ALLIS. [Vou. XII. 
fish the median aponeurosis from which the muscles in part 
arise is not so well developed as in the adult, and there are not 
the numerous intercrossing tendinous fibres found in the adult 
on the ventral surface of the aponeurosis and of the muscles 
themselves adjoining it. In its posterior portion the transversus, 
both in the young and in the adult, is continuous with the ante- 
rior portion of the constrictor of the pharynx. It is innervated 
by the nerve of the fifth arch, closely resembles the fifth inter- 
arcual of Acipenser (No. 125, Fig. 6), and is unquestionably the 
homologue of the proximal portion of the obliqui muscles of 
the anterior arches. 
c. Pharyngo-Clavicularis Externus and Internus. 
These two muscles (Pee and Pez) arise close together, usually 
as a single muscle, from the anterior surface of the clavicle 
immediately external to the dorsal portion of the sternohyoi- 
deus. The two muscles separate at once and the externus, 
which arises external to and below the internus, runs forward 
and medianward across that muscle and is inserted on the pos- 
terior or median edge of the ceratobranchial of the fifth arch 
near the middle of the bone, lying, at its insertion, median or 
posterior to the tendinous end of the second division of the 
fourth obliquus, and in front of the transversus posterior. 
The internus may be single or double, the two parts, when 
it is double, lying closely together but wholly separate except 
at their origins. The muscle runs forward and medianward 
across the transversus posterior and is inserted between that 
muscle and the transversus anterior on the anterior part of the 
third basibranchial. 
Both muscles are innervated by the nerve of the fifth arch 
and they are, in all probability, the homologues of the distal por- 
tions of the obliqui muscles of the anterior arches, that is, on 
the fourth arch, to muscle Ov./V?._ They are called by Schnei- 
der (No. III, p. 116), in ganoids and teleosts, the sterno- 
pharyngei, one being a rectus and the other an obliquus; by 
Albrecht (No. 2, pp. 29 and 34) they are called, in Acipenser, 
the interbranchialis internus VI, or omozonio-branchialis, and, 
in Gadus, the branchiretractor inferior and superior. 
