528 JULIA B. PLATT. 
the point where the primitive hyomandibular line meets the 
ventral longitudinal part, one, or sometimes two sense-organs 
extend towards the median surface of the throat. 
The otic sense-organ has not changed. 
From the more dorsal of the divisions of the glossopharyngeal 
ridge, seen in fig. 21, two or three sense-organs have developed. 
They do not usually lie in a vertical line, but lie often at an 
angle with one another, and may even be in a horizontal line, 
parallel to that occupied by the two sense-organs formed from 
the lower division of the glossopharyngeal ridge. 
Since the vertical line connected with the vagus is “ com- 
missural” in many fishes, I retain this designation, and would 
call attention to two sense-organs seen in fig. 32 posterior to 
the dorsal extremity of the line. These organs appear here 
exceptionally, for the vagus commissural line usually consists 
of a vertical row of organs, as in fig. 31. I consider the two 
organs just mentioned of interest, because they suggest a ten- 
dency to continue the dorsal lateral line of the trunk on to 
the head. The epibranchial line is now represented by four 
to six sense-organs. 
Not only is the number of sense-organs inconstant, but their 
position on both head and trunk is often unsymmetrical, and 
not infrequently an organ is found at some little distance from 
the line in which it properly belongs. 
The dorsal line of the trunk (fig. 32) does not extend beyond 
the anterior part of the tail. At the point where this line 
ends the median line leaves its position opposite the notochord, 
and as it grows backwards assumes a position similar to that 
occupied on the segments of the trunk by the dorsal line. The 
median line continues to the end of the tail. The ventral 
trunk line ends below the hind limb with a few sense-organs 
that lie much nearer to one another than do the organs in the 
median path of the line. The position of the organs on the 
dorsal line is often intersegmental, although an intersegment is 
occasionally omitted, or occasionally an organ lies above the 
myotome. 
To avoid confusion, in fig. 31, which shows the innervation 
