334 MR. E. W. SHANN ON THE 
evidence of the above observations the figures speak for them- 
selves ; but the essential features which I wish to emphasize are 
these :-— 
First, that the horizontal septum (f.s.) running from the 
lateral line to the vertebral centra is continuous ; also that the 
“red fibres” (r,f.) remain constant in position and extent, 
thereby showing that they form no part of the system of 
pyramids or cones. 
Text-figure 3. 
Two transverse sections through the dorsal moiety of the Jateral muscle of a 
young Salmon (34°5 mm.) taken from the pelvic region. 
A represents a plane ‘064 mm. anterior to B; 1-7, series of myomeres, identical 
in both sections; h.s., horizontal septum ; J.7., lateral line; 7.f., “red fibres” 
~~, arbitrary internal division-plane between the mesio-dorsal and latero- 
dorsal portions. 
Secondly, that the numbers are not merely written down 
symmetrically on either side of an arbitrary starting point. 
Where any two parts of myomeres are numbered as the same 
myomere, this has actually been proved to be the case by tracing 
their passage through a sufficient number of sections until they 
become confluent one with the other; to take an example, the 
separate parts denoted by the number 5 in A, become confluent 
when traced backwards to their position in B 5. 
Thirdly, that the ventral, forwardly directed pyramid is seen 
at its origin at A 1, and again, considerably increased in bulk, 
when traced backwards to its position at B 1; conversely, that 
the dorsal posteriorly-directed pyramid is seen decreasing from 
A7 to BZ. 
