VISCERAL ARCHES OP THE GNATHOSTOME FISHES. 369 
vented bv the one commissure formed, in this arch, in relation 
to the efferent arteries. The musculi interarcuales are also 
wanting in this arch, bnt it is said that in their place there is 
a complicated system of ligaments. It is not said that these 
ligaments are developed from any part of the myotome of the 
arch, but this would seem to be implied, the ligaments then 
representing the missing musculi interarcuales. In the 
ventral part of the arch the muscles are said to be found, 
undiminished in number, exactly as in the branchial arches. 
The distal portion of the myotome (Musculatur) is said to 
form the constrictor superficialis of the arch, which is richly 
developed, especially in its ventral portion. Dorsally this 
constrictor is said to turn posteriorly and fuse with the 
corresponding portion of the muscle of the first branchial 
arch. Ventrally, the distal portion of the constrictor is said 
to fuse with a similarly named portion of a myotome (Muskel- 
schlauches) which comes from the mandibular arch, tiie two 
muscles, together, then running ventrally and fusing with 
the fibres of the coracohyoideus and coracomandibularis 
exactly as the “ other coracobranchiales ” do (in der Weise 
der iirbigen M. coraco-branchiales). This expression evidently 
affirms that the distal portions of the ventral ends of the 
constrictores superficiales of the liyal and mandibular 
arches represent the coracobranchiales of those arches, and 
it would seem to imply that the coracobranchiales of the 
branchial arches were derived from the corresponding 
portions of the constrictores superficiales of their arches. 
But as, as has already been fully explained, the coraco- 
branchiales of DohriTs descriptions are said by him to be 
developed from the proximal portions of the myotomes of 
their respective arches, it must be that the coracobranchiales 
here referred to are the muscles so named by Vetter, but 
said by Dohrn to have been wrongly identified by him. What 
becomes of the remaining, proximal fibres of the ventral 
portion of the hyal myotome is not said, notwithstanding that 
they have been said to exist exactly as in the branchial arches. 
The descriptions are thus not clear, but it is important to note 
