sufficient to trace with accuracy the course of production in 
Phelps Lake in this year, they yield many suggestions of recur- 
rent pulses of production similar in duration, though of greater 
amplitude, to those more clearly defined in channel waters. A 
comparison of Plates XII. and XLII. will indicate the presence 
of pulses of production in both localities, culminating in the ma- 
jority of instances at approximately monthly intervals. There 
are eight such culminations in Phelps Lake visible in the rec- 
ords of March—December, culminating in March, May, June, 
July, August, September, November, and December. In spite 
of the disparity in the records in this lake and the river, the 
similarity in the location of the pulses in the two localities is 
apparent in all of the above months but August and November 
—hboth of which are months of unusual hydrographic disturb- 
ances in channel waters. 
A detailed comparison in the movement in production in 
this lake and the adjacent river shows agreement in the direc- 
tion of movement in 14 out of 21 possible instances,or 67 percent., 
5 of the 7 exceptions falling in the hydrographic disturbances in 
August-September and November. Inthe case of Quiver and 
Thompson’s lakesthe problem of comparison is made difficult be- 
cause the fortnightly collections in Phelps Lake and these local- 
ities are not upon coincident, butalternate, weeks, and makes the 
the similarity or difference probable rather than precise. A 
comparison shows 16 agreements out of a possible 20, or SO per 
cent., in the case of Thompson’s Lake, and 17 out of 20, or $5 per 
cent., in the case of Quiver Lake. Both of these lakes are af- 
fected by hydrographic changes at lower levels which do not 
disturb Phelps Lake, and we find that 6 of the 7 exceptions oc- 
cur in the period of floods at low levels. As a whole the move- 
ments in production in the lake in 1898 agree with those else- 
where in 47 out of 61 possible instances, or in 77 per cent. In 
view of the fact that the recordscover also the low-water period 
this is a notable degree of agreement, and is to be attributed 
to the unusually high average level for the year and to the 
equalizing effect of high water. This factor is not, however, in 
