158 BRODE. [Vou. XIV. 
3. SENSE ORGANS. 
(a) Descriptive. 
In common with other Oligochaetes the epidermis of Devo 
vaga is richly supplied with sense cells. These cells may occur 
isolated or in well-defined groups of from five to seven cells each. 
The isolated cells are scattered irregularly over the entire 
body and are more numerous on the anterior segments. On 
the first five or six segments there are at least three hundred 
of these cells to a segment. On the tenth segment and on the 
following segments the number is near fifty. 
The groups of cells, which I shall speak of as sense organs, 
have a very definite arrangement. They are found on every 
segment of the body and, excepting the first five segments, are 
arranged in two bands encircling the segment. The lesser band 
is found near the anterior part of the segment and the greater 
band passes through the setae in the posterior part of the 
segment. In the first segment the sense organs are very 
numerous and are irregularly distributed. The largest organs 
are on the anterior and dorso-lateral borders of the segment. 
At the dividing line between the first and second segments 
there is a band of organs, the exact number in which is not 
easily determined on account of the great number of isolated 
sense cells which occur on these segments. However, enough 
can be seen to determine that the organs are less numerous 
here than in the double bands in the next following segments, 
and, furthermore, that such organs as can be made out corre- 
spond in position to those in the lesser bands of the trunk 
segments. Segments II-V at first sight seem to possess 
but one band of organs, which occupies the position of the 
greater band in the other segments. Closer study shows that 
these organs are not exactly in the same line around the seg- 
ment; and, taking into account the fact that the number of 
organs in one of these bands corresponds to the number in the 
two bands of the other segments, I think we are justified in 
assuming that this band is a double band formed by the union 
of the greater and lesser band. 
