No. 3.} MUSCLES AND NERVES IN AMIA CALVA. 7O!I 
rather than not yet acquired, as Gegenbaur (No. 45) states to 
be the case for fishes in general. That such a condition should 
be found in Amia is only what might reasonably be expected 
if amphibians and ganoids both descend from some proto- 
urodelian type, as the muscles and nerves of the eyeball indi- 
cate (Fig. 12, Pl. XXII). It is perhaps worthy of note, in this 
connection, that the branchiomandibularis is found in Acipenser 
(Vetter) and Polypterus (Pollard), that it is not found in teleosts, 
and that it is found, undifferentiated, as Muscle Cm1, or Cmz, 
in Chimaera (Vetter). 
The branchiomandibularis is innervated, in Amia, by a deli- 
cate terminal branch (7.6m) of the fused ventral branches of 
the first, second, and third occipital nerves. 
2. Sternohyoideus. 
The sternohyoideus (S%, Figs. 33-35, 46, and 57, Pls. 
XXVITI-XXXV) arises from the dorsal and anterior surface of 
the lower half of the clavicle, the surface of origin extending 
from the symphysis of the bones up to the place of origin of 
the pharyngo-claviculares. It is a strong, conical muscle lying 
immediately below the bulbus arteriosus, and tapering grad- 
ually into a stout, rounded tendon which is inserted on the 
ventral surface of the ossified portion of the hypohyal. It is 
closely united with its fellow of the opposite side of the head 
from its origin forward, through about one half its length, the 
two muscles being separated by a median aponeurosis, from 
which the fibres of both in part arise. This aponeurosis is 
strongest toward the dorsal surface of the muscle, and from its 
anterior end arise the two arms of the tendon Caa+, to which 
the branchiomandibularis is inserted. 
Through each sternohyoideus there are two transverse inter- 
muscular septa, resembling the intermuscular septa of the 
trunk muscles, and dividing each muscle into three parts. 
The middle point of each septum (Fig. 35) is pulled forward 
into a pocket, and on the anterior face of the septum, around 
the pocket, there is a conical tuft of connective tissue. A 
similar tuft is found on the corresponding point of the ante- 
