670 ALETS. [Vox. XII. 
levator arc. branch. int. post. and external to that of the retractor 
arc. branch. It lies in part, at its origin, ventral to the anterior 
end of the latter muscle, runs outward and backward across the 
dorsal or internal surface of the levator arc. branch. int. post., 
and is inserted on the posterior edge of the median of the three 
processes on the proximal end of the fourth epibranchial. The 
second obliquus (Od?) arises from the dorsal surface of this 
same process, runs almost directly backward to the anterior 
end of the pharynx, then turns downward, and is inserted along 
the posterior edge of the proximal end of the fifth ceratobran- 
chial. The third obliquus (Od) arises from the upper surface 
of the third infrapharyngobranchial median to the posterior 
process of the proximal end of the fourth epibranchial, runs 
outward and backward across the ligament connecting that 
process with the infrapharyngobranchial, then turns downward 
and becomes continuous with the constrictor of the pharynx. 
The anterior obliquus is innervated by a branch of the vagus 
that supplies also the retractor arc. branch. The other two 
obliqui are innervated by branches of the vagus that innervate 
the constrictor of the pharynx. 
b. Transversi Dorsales. 
The anterior transversus (7da) arises from the upper surface 
of the anterior portion of the third infrapharyngobranchial, the 
surface of origin extending to the extreme lateral edge of the 
piece, and the muscle lying, in this part, under and external to 
the levator arc. branch. int. post. The fibres of the muscle 
have a curved course, running at first forward and medianward 
under the levator, then medianward, and then medianward and 
backward, to the middle line of the head. The fibres in the 
middle portion only of the muscle have a fairly straight course 
from one side of the head to the other. In its anterior portion, 
in the middle line, it is somewhat fibrous, and is here closely 
attached to the base of the skull. In 40mm. specimens the 
fibres at this point interlace. The muscle is continuous in its 
deeper portion with the retractor, and is innervated by the 
nerve that innervates the anterior obliquus and also the retrac- 
tor. The transversus posterior (7d) arises from the posterior 
