366 CHIKANOSUKE OGAWA 
2. Muscle fibers in Reptilia 
Clemmys japonicus. The arrangement of the muscle fibers 
in the septum and the outer lung wall is the same as in Rana and 
Megalobatrachus; that is to say, the muscle bundles of various 
strengths interweave with each other, and among these the 
individual fibers may be seen. The free edges of septa come 
together from three or four directions. There are two ways in 
which the muscle fibers interweave in those portions where three 
free edges come together, as will be seen in figure 24. All three 
free edges exchange their muscle fibers as a, b, c, or only two 
adjacent edges exchange their fibers as a-b, a-c, in which no 
fibers connect b and c. In such a case b and ¢ form usually a 
sharper angle. Where four free edges are merged, the muscle 
fibers are not only exchanged between adjacent, but also with 
those free edges directly opposite. Since the free edge in the 
tortoise is much thicker than that of Rana, the muscle fibers 
are of correspondingly greater strength in the former than in the 
latter. The muscle fibers of the free edges of the primary septa 
are not flat, such as in Megalobatrachus, but somewhat cir- 
cular in section. This is true of the lower orders of septa as 
well. 
Gecko japonicus. The muscle bundles in the free edges of the 
septa interweave each other just in the same manner as in the 
tortoise. The muscle bundles, which start from the free edges 
of septa and run therein, are weakest compared to the animals 
before mentioned. Observed in surface view, the bundles in 
the outer lung wall are also weak, but the fibers which are at 
right angles to the septa in the outer wall are somewhat stronger. 
They must be considered as incompletely developed septa be- 
cause of their course and because they form small prominence 
on the wall. 
Elaphe quadrivirgata. The muscle bundles in the edges of the 
primary septa are fairly well developed. Yet the bundles in 
septa themselves are not developed to a corresponding extent, 
sometimes even consisting of but a few fibers. From septa of 
the lower orders there are formed septa which run parallel to 
