562 
CAPTAIN E. W. SHANN ON 
The protractor pectoralis is invariably divided into two distinct portions, as 
described below. 
(i) P.p. anterior. 
This part of the muscle is usually slightly internal to the succeeding part. In 
point of size it may be larger, as in I Zeus faber (fig. 16), or smaller, as in Lophius 
piscatorius (fig. 22), than the succeeding portion. The insertion is entirely upon the 
cleithrum, but may take place upon the inner aspect (Zeus), or upon the outer aspect 
(Lophius). 
(ii) P.p. posterior. 
This part of the muscle arises behind the former and is inserted partly upon the 
supraclavicle, and, to a greater or less extent, upon the cleithrum. 
(b i) Levator pectoralis. Diaphragmamuskel, Cuvier ; Trapezoide, 
Vogt and Yung ; Levator, Hamburger ; Sternocleido-mastoideus, 
Humphry. 
A flattened columnar muscle underlies the foregoing muscles. It arises from the 
basioccipital or parasphenoid and is inserted on the inner aspect of the cleithrum. 
This muscle usually forms the lateral wall of the pericardium, and for that reason 
was named by Cuvier “ diaphragmamuskel.” 
It should be recalled that this muscle is absent in the Sturgeon ; in many 
Teleosteans it is exceedingly minute, and in Motella it is absent, unless it is represented 
in that form by the ligament (figs. 19, 20) which runs from the inner aspect of the 
cleithrum to the basioccipital. I am inclined to believe that this is not the case, 
for both in Trigla and Lophius, which possess .a normal levator pectoralis, the liga- 
ment is present in addition. It is curious that in Lophius this ligament, instead of 
being inserted on the side of the basioccipital or of the vertebral centra (as in the 
majority of Teleosteans), unites with its fellow of the opposite side in the space 
between the kidney and the vertebral column. 
B. Connections with the Visceral Arches. 
(b ii) Cleithro - branchialis. Branchiretractors, Owen ; Pharyngo- 
clavicularis, Vogt and Yung, M‘Murrich ; Branchio-clavicularis, 
Hamburger. 
Two compact little bands of muscle invariably run from the anterior border of 
the cleithrum to the fourth ceratobranchial. The two muscles run approximately at 
right angles to one another, and their insertions on the ceratobranchial are usually 
close together, or even contiguous (Zeus). 
a. Cli. br. externus. 
This muscle arises from the lower third of the cleithrum, and follows an approxi- 
mately vertical course (Zeus, fig. 16). In Motella (fig. 20) the muscle runs obliquely 
upwards. In Trigla the muscle is traversed by two transverse septa. 
